[SPARK-18872][SQL][TESTS] New test cases for EXISTS subquery

## What changes were proposed in this pull request?
This PR adds the first set of tests for EXISTS subquery.

File name                        | Brief description
------------------------| -----------------
exists-basic.sql              |Tests EXISTS and NOT EXISTS subqueries with both correlated and local predicates.
exists-within-and-or.sql|Tests EXISTS and NOT EXISTS subqueries embedded in AND or OR expression.

DB2 results are attached here as reference :

[exists-basic-db2.txt](https://github.com/apache/spark/files/733031/exists-basic-db2.txt)
[exists-and-or-db2.txt](https://github.com/apache/spark/files/733030/exists-and-or-db2.txt)

## How was this patch tested?
This patch is adding tests.

Author: Dilip Biswal <dbiswal@us.ibm.com>

Closes #16710 from dilipbiswal/exist-basic.

sql/core/src/test/resources/sql-tests/inputs/subquery/exists-subquery/exists-basic.sql

+-- Tests EXISTS subquery support. Tests basic form 
+-- of EXISTS subquery (both EXISTS and NOT EXISTS)
+
+CREATE TEMPORARY VIEW EMP AS SELECT * FROM VALUES
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (200, "emp 2", date "2003-01-01", 200.00D, 10),
+  (300, "emp 3", date "2002-01-01", 300.00D, 20),
+  (400, "emp 4", date "2005-01-01", 400.00D, 30),
+  (500, "emp 5", date "2001-01-01", 400.00D, NULL),
+  (600, "emp 6 - no dept", date "2001-01-01", 400.00D, 100),
+  (700, "emp 7", date "2010-01-01", 400.00D, 100),
+  (800, "emp 8", date "2016-01-01", 150.00D, 70)
+AS EMP(id, emp_name, hiredate, salary, dept_id);
+
+CREATE TEMPORARY VIEW DEPT AS SELECT * FROM VALUES
+  (10, "dept 1", "CA"),
+  (20, "dept 2", "NY"),
+  (30, "dept 3", "TX"),
+  (40, "dept 4 - unassigned", "OR"),
+  (50, "dept 5 - unassigned", "NJ"),
+  (70, "dept 7", "FL")
+AS DEPT(dept_id, dept_name, state);
+
+CREATE TEMPORARY VIEW BONUS AS SELECT * FROM VALUES
+  ("emp 1", 10.00D),
+  ("emp 1", 20.00D),
+  ("emp 2", 300.00D),
+  ("emp 2", 100.00D),
+  ("emp 3", 300.00D),
+  ("emp 4", 100.00D),
+  ("emp 5", 1000.00D),
+  ("emp 6 - no dept", 500.00D)
+AS BONUS(emp_name, bonus_amt);
+
+-- uncorrelated exist query 
+-- TC.01.01
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT 1 
+               FROM   dept 
+               WHERE  dept.dept_id > 10 
+                      AND dept.dept_id < 30); 
+
+-- simple correlated predicate in exist subquery
+-- TC.01.02
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id); 
+
+-- correlated outer isnull predicate
+-- TC.01.03
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id 
+                       OR emp.dept_id IS NULL);
+
+-- Simple correlation with a local predicate in outer query
+-- TC.01.04
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+       AND emp.id > 200; 
+
+-- Outer references (emp.id) should not be pruned from outer plan
+-- TC.01.05
+SELECT emp.emp_name 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.state 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+       AND emp.id > 200;
+
+-- not exists with correlated predicate
+-- TC.01.06
+SELECT * 
+FROM   dept 
+WHERE  NOT EXISTS (SELECT emp_name 
+                   FROM   emp 
+                   WHERE  emp.dept_id = dept.dept_id);
+
+-- not exists with correlated predicate + local predicate
+-- TC.01.07
+SELECT * 
+FROM   dept 
+WHERE  NOT EXISTS (SELECT emp_name 
+                   FROM   emp 
+                   WHERE  emp.dept_id = dept.dept_id 
+                           OR state = 'NJ');
+
+-- not exist both equal and greaterthan predicate
+-- TC.01.08
+SELECT * 
+FROM   bonus 
+WHERE  NOT EXISTS (SELECT * 
+                   FROM   emp 
+                   WHERE  emp.emp_name = emp_name 
+                          AND bonus_amt > emp.salary); 
+
+-- select employees who have not received any bonus
+-- TC 01.09
+SELECT emp.*
+FROM   emp
+WHERE  NOT EXISTS (SELECT NULL
+                   FROM   bonus
+                   WHERE  bonus.emp_name = emp.emp_name);
+
+-- Nested exists
+-- TC.01.10
+SELECT * 
+FROM   bonus 
+WHERE  EXISTS (SELECT emp_name 
+               FROM   emp 
+               WHERE  bonus.emp_name = emp.emp_name 
+                      AND EXISTS (SELECT state 
+                                  FROM   dept 
+                                  WHERE  dept.dept_id = emp.dept_id)); 

sql/core/src/test/resources/sql-tests/inputs/subquery/exists-subquery/exists-within-and-or.sql

+-- Tests EXISTS subquery support. Tests EXISTS 
+-- subquery within a AND or OR expression.
+
+CREATE TEMPORARY VIEW EMP AS SELECT * FROM VALUES
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (200, "emp 2", date "2003-01-01", 200.00D, 10),
+  (300, "emp 3", date "2002-01-01", 300.00D, 20),
+  (400, "emp 4", date "2005-01-01", 400.00D, 30),
+  (500, "emp 5", date "2001-01-01", 400.00D, NULL),
+  (600, "emp 6 - no dept", date "2001-01-01", 400.00D, 100),
+  (700, "emp 7", date "2010-01-01", 400.00D, 100),
+  (800, "emp 8", date "2016-01-01", 150.00D, 70)
+AS EMP(id, emp_name, hiredate, salary, dept_id);
+
+CREATE TEMPORARY VIEW DEPT AS SELECT * FROM VALUES
+  (10, "dept 1", "CA"),
+  (20, "dept 2", "NY"),
+  (30, "dept 3", "TX"),
+  (40, "dept 4 - unassigned", "OR"),
+  (50, "dept 5 - unassigned", "NJ"),
+  (70, "dept 7", "FL")
+AS DEPT(dept_id, dept_name, state);
+
+CREATE TEMPORARY VIEW BONUS AS SELECT * FROM VALUES
+  ("emp 1", 10.00D),
+  ("emp 1", 20.00D),
+  ("emp 2", 300.00D),
+  ("emp 2", 100.00D),
+  ("emp 3", 300.00D),
+  ("emp 4", 100.00D),
+  ("emp 5", 1000.00D),
+  ("emp 6 - no dept", 500.00D)
+AS BONUS(emp_name, bonus_amt);
+
+
+-- Or used in conjunction with exists - ExistenceJoin
+-- TC.02.01
+SELECT emp.emp_name 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.state 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+        OR emp.id > 200;
+
+-- all records from emp including the null dept_id 
+-- TC.02.02
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+        OR emp.dept_id IS NULL; 
+
+-- EXISTS subquery in both LHS and RHS of OR. 
+-- TC.02.03
+SELECT emp.emp_name 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.state 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id 
+                      AND dept.dept_id = 20) 
+        OR EXISTS (SELECT dept.state 
+                   FROM   dept 
+                   WHERE  emp.dept_id = dept.dept_id 
+                          AND dept.dept_id = 30); 
+;
+
+-- not exists and exists predicate within OR
+-- TC.02.04
+SELECT * 
+FROM   bonus 
+WHERE  ( NOT EXISTS (SELECT * 
+                     FROM   emp 
+                     WHERE  emp.emp_name = emp_name 
+                            AND bonus_amt > emp.salary) 
+          OR EXISTS (SELECT * 
+                     FROM   emp 
+                     WHERE  emp.emp_name = emp_name 
+                             OR bonus_amt < emp.salary) );
+
+-- not exists and in predicate within AND
+-- TC.02.05
+SELECT * FROM bonus WHERE NOT EXISTS 
+( 
+       SELECT * 
+       FROM   emp 
+       WHERE  emp.emp_name = emp_name 
+       AND    bonus_amt > emp.salary) 
+AND 
+emp_name IN 
+( 
+       SELECT emp_name 
+       FROM   emp 
+       WHERE  bonus_amt < emp.salary);
+

sql/core/src/test/resources/sql-tests/results/subquery/exists-subquery/exists-basic.sql.out

+-- Automatically generated by SQLQueryTestSuite
+-- Number of queries: 13
+
+
+-- !query 0
+CREATE TEMPORARY VIEW EMP AS SELECT * FROM VALUES
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (200, "emp 2", date "2003-01-01", 200.00D, 10),
+  (300, "emp 3", date "2002-01-01", 300.00D, 20),
+  (400, "emp 4", date "2005-01-01", 400.00D, 30),
+  (500, "emp 5", date "2001-01-01", 400.00D, NULL),
+  (600, "emp 6 - no dept", date "2001-01-01", 400.00D, 100),
+  (700, "emp 7", date "2010-01-01", 400.00D, 100),
+  (800, "emp 8", date "2016-01-01", 150.00D, 70)
+AS EMP(id, emp_name, hiredate, salary, dept_id)
+-- !query 0 schema
+struct<>
+-- !query 0 output
+
+
+
+-- !query 1
+CREATE TEMPORARY VIEW DEPT AS SELECT * FROM VALUES
+  (10, "dept 1", "CA"),
+  (20, "dept 2", "NY"),
+  (30, "dept 3", "TX"),
+  (40, "dept 4 - unassigned", "OR"),
+  (50, "dept 5 - unassigned", "NJ"),
+  (70, "dept 7", "FL")
+AS DEPT(dept_id, dept_name, state)
+-- !query 1 schema
+struct<>
+-- !query 1 output
+
+
+
+-- !query 2
+CREATE TEMPORARY VIEW BONUS AS SELECT * FROM VALUES
+  ("emp 1", 10.00D),
+  ("emp 1", 20.00D),
+  ("emp 2", 300.00D),
+  ("emp 2", 100.00D),
+  ("emp 3", 300.00D),
+  ("emp 4", 100.00D),
+  ("emp 5", 1000.00D),
+  ("emp 6 - no dept", 500.00D)
+AS BONUS(emp_name, bonus_amt)
+-- !query 2 schema
+struct<>
+-- !query 2 output
+
+
+
+-- !query 3
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT 1 
+               FROM   dept 
+               WHERE  dept.dept_id > 10 
+                      AND dept.dept_id < 30)
+-- !query 3 schema
+struct<id:int,emp_name:string,hiredate:date,salary:double,dept_id:int>
+-- !query 3 output
+100	emp 1	2005-01-01	100.0	10
+100	emp 1	2005-01-01	100.0	10
+200	emp 2	2003-01-01	200.0	10
+300	emp 3	2002-01-01	300.0	20
+400	emp 4	2005-01-01	400.0	30
+500	emp 5	2001-01-01	400.0	NULL
+600	emp 6 - no dept	2001-01-01	400.0	100
+700	emp 7	2010-01-01	400.0	100
+800	emp 8	2016-01-01	150.0	70
+
+
+-- !query 4
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id)
+-- !query 4 schema
+struct<id:int,emp_name:string,hiredate:date,salary:double,dept_id:int>
+-- !query 4 output
+100	emp 1	2005-01-01	100.0	10
+100	emp 1	2005-01-01	100.0	10
+200	emp 2	2003-01-01	200.0	10
+300	emp 3	2002-01-01	300.0	20
+400	emp 4	2005-01-01	400.0	30
+800	emp 8	2016-01-01	150.0	70
+
+
+-- !query 5
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id 
+                       OR emp.dept_id IS NULL)
+-- !query 5 schema
+struct<id:int,emp_name:string,hiredate:date,salary:double,dept_id:int>
+-- !query 5 output
+100	emp 1	2005-01-01	100.0	10
+100	emp 1	2005-01-01	100.0	10
+200	emp 2	2003-01-01	200.0	10
+300	emp 3	2002-01-01	300.0	20
+400	emp 4	2005-01-01	400.0	30
+500	emp 5	2001-01-01	400.0	NULL
+800	emp 8	2016-01-01	150.0	70
+
+
+-- !query 6
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+       AND emp.id > 200
+-- !query 6 schema
+struct<id:int,emp_name:string,hiredate:date,salary:double,dept_id:int>
+-- !query 6 output
+300	emp 3	2002-01-01	300.0	20
+400	emp 4	2005-01-01	400.0	30
+800	emp 8	2016-01-01	150.0	70
+
+
+-- !query 7
+SELECT emp.emp_name 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.state 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+       AND emp.id > 200
+-- !query 7 schema
+struct<emp_name:string>
+-- !query 7 output
+emp 3
+emp 4
+emp 8
+
+
+-- !query 8
+SELECT * 
+FROM   dept 
+WHERE  NOT EXISTS (SELECT emp_name 
+                   FROM   emp 
+                   WHERE  emp.dept_id = dept.dept_id)
+-- !query 8 schema
+struct<dept_id:int,dept_name:string,state:string>
+-- !query 8 output
+40	dept 4 - unassigned	OR
+50	dept 5 - unassigned	NJ
+
+
+-- !query 9
+SELECT * 
+FROM   dept 
+WHERE  NOT EXISTS (SELECT emp_name 
+                   FROM   emp 
+                   WHERE  emp.dept_id = dept.dept_id 
+                           OR state = 'NJ')
+-- !query 9 schema
+struct<dept_id:int,dept_name:string,state:string>
+-- !query 9 output
+40	dept 4 - unassigned	OR
+
+
+-- !query 10
+SELECT * 
+FROM   bonus 
+WHERE  NOT EXISTS (SELECT * 
+                   FROM   emp 
+                   WHERE  emp.emp_name = emp_name 
+                          AND bonus_amt > emp.salary)
+-- !query 10 schema
+struct<emp_name:string,bonus_amt:double>
+-- !query 10 output
+emp 1	10.0
+emp 1	20.0
+emp 2	100.0
+emp 4	100.0
+
+
+-- !query 11
+SELECT emp.*
+FROM   emp
+WHERE  NOT EXISTS (SELECT NULL
+                   FROM   bonus
+                   WHERE  bonus.emp_name = emp.emp_name)
+-- !query 11 schema
+struct<id:int,emp_name:string,hiredate:date,salary:double,dept_id:int>
+-- !query 11 output
+700	emp 7	2010-01-01	400.0	100
+800	emp 8	2016-01-01	150.0	70
+
+
+-- !query 12
+SELECT * 
+FROM   bonus 
+WHERE  EXISTS (SELECT emp_name 
+               FROM   emp 
+               WHERE  bonus.emp_name = emp.emp_name 
+                      AND EXISTS (SELECT state 
+                                  FROM   dept 
+                                  WHERE  dept.dept_id = emp.dept_id))
+-- !query 12 schema
+struct<emp_name:string,bonus_amt:double>
+-- !query 12 output
+emp 1	10.0
+emp 1	20.0
+emp 2	100.0
+emp 2	300.0
+emp 3	300.0
+emp 4	100.0

sql/core/src/test/resources/sql-tests/results/subquery/exists-subquery/exists-within-and-or.sql.out

+-- Automatically generated by SQLQueryTestSuite
+-- Number of queries: 8
+
+
+-- !query 0
+CREATE TEMPORARY VIEW EMP AS SELECT * FROM VALUES
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (100, "emp 1", date "2005-01-01", 100.00D, 10),
+  (200, "emp 2", date "2003-01-01", 200.00D, 10),
+  (300, "emp 3", date "2002-01-01", 300.00D, 20),
+  (400, "emp 4", date "2005-01-01", 400.00D, 30),
+  (500, "emp 5", date "2001-01-01", 400.00D, NULL),
+  (600, "emp 6 - no dept", date "2001-01-01", 400.00D, 100),
+  (700, "emp 7", date "2010-01-01", 400.00D, 100),
+  (800, "emp 8", date "2016-01-01", 150.00D, 70)
+AS EMP(id, emp_name, hiredate, salary, dept_id)
+-- !query 0 schema
+struct<>
+-- !query 0 output
+
+
+
+-- !query 1
+CREATE TEMPORARY VIEW DEPT AS SELECT * FROM VALUES
+  (10, "dept 1", "CA"),
+  (20, "dept 2", "NY"),
+  (30, "dept 3", "TX"),
+  (40, "dept 4 - unassigned", "OR"),
+  (50, "dept 5 - unassigned", "NJ"),
+  (70, "dept 7", "FL")
+AS DEPT(dept_id, dept_name, state)
+-- !query 1 schema
+struct<>
+-- !query 1 output
+
+
+
+-- !query 2
+CREATE TEMPORARY VIEW BONUS AS SELECT * FROM VALUES
+  ("emp 1", 10.00D),
+  ("emp 1", 20.00D),
+  ("emp 2", 300.00D),
+  ("emp 2", 100.00D),
+  ("emp 3", 300.00D),
+  ("emp 4", 100.00D),
+  ("emp 5", 1000.00D),
+  ("emp 6 - no dept", 500.00D)
+AS BONUS(emp_name, bonus_amt)
+-- !query 2 schema
+struct<>
+-- !query 2 output
+
+
+
+-- !query 3
+SELECT emp.emp_name 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.state 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+        OR emp.id > 200
+-- !query 3 schema
+struct<emp_name:string>
+-- !query 3 output
+emp 1
+emp 1
+emp 2
+emp 3
+emp 4
+emp 5
+emp 6 - no dept
+emp 7
+emp 8
+
+
+-- !query 4
+SELECT * 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.dept_name 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id) 
+        OR emp.dept_id IS NULL
+-- !query 4 schema
+struct<id:int,emp_name:string,hiredate:date,salary:double,dept_id:int>
+-- !query 4 output
+100	emp 1	2005-01-01	100.0	10
+100	emp 1	2005-01-01	100.0	10
+200	emp 2	2003-01-01	200.0	10
+300	emp 3	2002-01-01	300.0	20
+400	emp 4	2005-01-01	400.0	30
+500	emp 5	2001-01-01	400.0	NULL
+800	emp 8	2016-01-01	150.0	70
+
+
+-- !query 5
+SELECT emp.emp_name 
+FROM   emp 
+WHERE  EXISTS (SELECT dept.state 
+               FROM   dept 
+               WHERE  emp.dept_id = dept.dept_id 
+                      AND dept.dept_id = 20) 
+        OR EXISTS (SELECT dept.state 
+                   FROM   dept 
+                   WHERE  emp.dept_id = dept.dept_id 
+                          AND dept.dept_id = 30)
+-- !query 5 schema
+struct<emp_name:string>
+-- !query 5 output
+emp 3
+emp 4
+
+
+-- !query 6
+SELECT * 
+FROM   bonus 
+WHERE  ( NOT EXISTS (SELECT * 
+                     FROM   emp 
+                     WHERE  emp.emp_name = emp_name 
+                            AND bonus_amt > emp.salary) 
+          OR EXISTS (SELECT * 
+                     FROM   emp 
+                     WHERE  emp.emp_name = emp_name 
+                             OR bonus_amt < emp.salary) )
+-- !query 6 schema
+struct<emp_name:string,bonus_amt:double>
+-- !query 6 output
+emp 1	10.0
+emp 1	20.0
+emp 2	100.0
+emp 2	300.0
+emp 3	300.0
+emp 4	100.0
+emp 5	1000.0
+emp 6 - no dept	500.0
+
+
+-- !query 7
+SELECT * FROM bonus WHERE NOT EXISTS 
+( 
+       SELECT * 
+       FROM   emp 
+       WHERE  emp.emp_name = emp_name 
+       AND    bonus_amt > emp.salary) 
+AND 
+emp_name IN 
+( 
+       SELECT emp_name 
+       FROM   emp 
+       WHERE  bonus_amt < emp.salary)
+-- !query 7 schema
+struct<emp_name:string,bonus_amt:double>
+-- !query 7 output
+emp 1	10.0
+emp 1	20.0
+emp 2	100.0
+emp 4	100.0