[SPARK-35977][SQL] Support non-reserved keyword TIMESTAMP_NTZ

### What changes were proposed in this pull request?

Support new keyword TIMESTAMP_NTZ, which can be used for:

- timestamp without time zone data type in DDL
- timestamp without time zone data type in Cast clause.
- timestamp without time zone data type literal

### Why are the changes needed?

Users can use `TIMESTAMP_NTZ` in DDL/Cast/Literals for the timestamp without time zone type directly.

### Does this PR introduce _any_ user-facing change?

No, the new timestamp type is not released yet.

### How was this patch tested?

Unit test

Closes #33221 from gengliangwang/timstamp_ntz.

Authored-by: Gengliang Wang <gengliang@apache.org>
Signed-off-by: Max Gekk <max.gekk@gmail.com>
(cherry picked from commit 5f44acff3d)
Signed-off-by: Max Gekk <max.gekk@gmail.com>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala

@@ -2125,6 +2125,9 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef] with SQLConfHelper with Logg
           val zoneId = getZoneId(conf.sessionLocalTimeZone)
           val specialDate = convertSpecialDate(value, zoneId).map(Literal(_, DateType))
           specialDate.getOrElse(toLiteral(stringToDate, DateType))
+        case "TIMESTAMP_NTZ" =>
+          val specialTs = convertSpecialTimestampNTZ(value).map(Literal(_, TimestampNTZType))
+          specialTs.getOrElse(toLiteral(stringToTimestampWithoutTimeZone, TimestampNTZType))
         case "TIMESTAMP" =>
           def constructTimestampLTZLiteral(value: String): Literal = {
             val zoneId = getZoneId(conf.sessionLocalTimeZone)
@@ -2525,6 +2528,7 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef] with SQLConfHelper with Logg
       case ("double", Nil) => DoubleType
       case ("date", Nil) => DateType
       case ("timestamp", Nil) => SQLConf.get.timestampType
+      case ("timestamp_ntz", Nil) => TimestampNTZType
       case ("string", Nil) => StringType
       case ("character" | "char", length :: Nil) => CharType(length.getText.toInt)
       case ("varchar", length :: Nil) => VarcharType(length.getText.toInt)

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/DataTypeParserSuite.scala

@@ -58,6 +58,7 @@ class DataTypeParserSuite extends SparkFunSuite with SQLHelper {
   checkDataType("deC", DecimalType.USER_DEFAULT)
   checkDataType("DATE", DateType)
   checkDataType("timestamp", TimestampType)
+  checkDataType("timestamp_ntz", TimestampNTZType)
   checkDataType("string", StringType)
   checkDataType("ChaR(5)", CharType(5))
   checkDataType("ChaRacter(5)", CharType(5))

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ExpressionParserSuite.scala

@@ -465,6 +465,9 @@ class ExpressionParserSuite extends AnalysisTest {
     intercept("timestamP '2016-33-11 20:54:00.000'", "Cannot parse the TIMESTAMP value")
 
     // Timestamp without time zone
+    assertEqual("tImEstAmp_Ntz '2016-03-11 20:54:00.000'",
+      Literal(LocalDateTime.parse("2016-03-11T20:54:00.000")))
+    intercept("tImEstAmp_Ntz '2016-33-11 20:54:00.000'", "Cannot parse the TIMESTAMP_NTZ value")
     withSQLConf(SQLConf.TIMESTAMP_TYPE.key -> TimestampTypes.TIMESTAMP_NTZ.toString) {
       assertEqual("tImEstAmp '2016-03-11 20:54:00.000'",
         Literal(LocalDateTime.parse("2016-03-11T20:54:00.000")))