Re-add convertToScala(), since a Hive test still needs it

Author: JoshRosen

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/CatalystTypeConverters.scala

@@ -353,6 +353,15 @@ object CatalystTypeConverters {
     case other => other
   }
 
+  /**
+   * Converts Catalyst types used internally in rows to standard Scala types
+   * This method is slow, and for batch conversion you should be using converter
+   * produced by createToScalaConverter.
+   */
+  def convertToScala(catalystValue: Any, dataType: DataType): Any = {
+    getConverterForType(dataType).toScala(catalystValue)
+  }
+
   /**
    * Creates a converter function that will convert Catalyst types to Scala type.
    * Typical use case would be converting a collection of rows that have the same schema. You will