[SPARK-20281][SQL] Print the identical Range parameters of SparkContext APIs and SQL in explain

## What changes were proposed in this pull request?
This pr modified code to print the identical `Range` parameters of SparkContext APIs and SQL in `explain` output. In the current master, they internally use `defaultParallelism` for `splits` by default though, they print different strings in explain output;

```
scala> spark.range(4).explain
== Physical Plan ==
*Range (0, 4, step=1, splits=Some(8))

scala> sql("select * from range(4)").explain
== Physical Plan ==
*Range (0, 4, step=1, splits=None)
```

## How was this patch tested?
Added tests in `SQLQuerySuite` and modified some results in the existing tests.

Author: Takeshi Yamamuro <yamamuro@apache.org>

Closes #17670 from maropu/SPARK-20281.

sql/core/src/main/scala/org/apache/spark/sql/execution/basicPhysicalOperators.scala

@@ -332,6 +332,7 @@ case class RangeExec(range: org.apache.spark.sql.catalyst.plans.logical.Range)
   extends LeafExecNode with CodegenSupport {
 
   def start: Long = range.start
+  def end: Long = range.end
   def step: Long = range.step
   def numSlices: Int = range.numSlices.getOrElse(sparkContext.defaultParallelism)
   def numElements: BigInt = range.numElements
@@ -538,7 +539,7 @@ case class RangeExec(range: org.apache.spark.sql.catalyst.plans.logical.Range)
       }
   }
 
-  override def simpleString: String = range.simpleString
+  override def simpleString: String = s"Range ($start, $end, step=$step, splits=$numSlices)"
 }
 
 /**

sql/core/src/test/resources/sql-tests/results/sql-compatibility-functions.sql.out

@@ -88,7 +88,7 @@ Project [coalesce(cast(id#xL as string), x) AS ifnull(`id`, 'x')#x, id#xL AS nul
 
 == Physical Plan ==
 *Project [coalesce(cast(id#xL as string), x) AS ifnull(`id`, 'x')#x, id#xL AS nullif(`id`, 'x')#xL, coalesce(cast(id#xL as string), x) AS nvl(`id`, 'x')#x, x AS nvl2(`id`, 'x', 'y')#x]
-+- *Range (0, 2, step=1, splits=None)
++- *Range (0, 2, step=1, splits=2)
 
 
 -- !query 9

sql/core/src/test/resources/sql-tests/results/table-valued-functions.sql.out

@@ -102,4 +102,4 @@ EXPLAIN select * from RaNgE(2)
 struct<plan:string>
 -- !query 8 output
 == Physical Plan ==
-*Range (0, 2, step=1, splits=None)
+*Range (0, 2, step=1, splits=2)