[SPARK-16340][SQL] Support column arguments for `regexp_replace` Dataset operation

## What changes were proposed in this pull request?

Currently, `regexp_replace` function supports `Column` arguments in a query. This PR supports that in a `Dataset` operation, too.

## How was this patch tested?

Pass the Jenkins tests with a updated testcase.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #14060 from dongjoon-hyun/SPARK-16340.

sql/core/src/main/scala/org/apache/spark/sql/functions.scala

@@ -2193,6 +2193,16 @@ object functions {
     RegExpReplace(e.expr, lit(pattern).expr, lit(replacement).expr)
   }
 
+  /**
+   * Replace all substrings of the specified string value that match regexp with rep.
+   *
+   * @group string_funcs
+   * @since 2.1.0
+   */
+  def regexp_replace(e: Column, pattern: Column, replacement: Column): Column = withExpr {
+    RegExpReplace(e.expr, pattern.expr, replacement.expr)
+  }
+
   /**
    * Decodes a BASE64 encoded string column and returns it as a binary column.
    * This is the reverse of base64.

sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala

@@ -77,8 +77,10 @@ class StringFunctionsSuite extends QueryTest with SharedSQLContext {
     checkAnswer(
       df.select(
         regexp_replace($"a", "(\\d+)", "num"),
+        regexp_replace($"a", $"b", $"c"),
         regexp_extract($"a", "(\\d+)-(\\d+)", 1)),
-      Row("num-num", "100") :: Row("num-num", "100") :: Row("num-num", "100") :: Nil)
+      Row("num-num", "300", "100") :: Row("num-num", "400", "100") ::
+        Row("num-num", "400-400", "100") :: Nil)
 
     // for testing the mutable state of the expression in code gen.
     // This is a hack way to enable the codegen, thus the codegen is enable by default,