[FLINK-27014][hive] Fix exception when select null literal in subquery for Hive dialect

[luoyuxia]

What is the purpose of the change

To fix the exception when select null literal in subquery for Hive dialect

Brief change log

• Consider Hive's void type as a null varchar type instead of null type in HiveParserRexNodeConverter#convertConstant just like what has been done in HiveInspectors#getObjectInspectorForPrimitiveConstant for Flink dosen't support null type.

Verifying this change

Add test query in flink-connectors/flink-connector-hive/src/test/resources/query-test/misc.q

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? NA

[flinkbot]

CI report:

• fc0bc78fcdf4db9eddd9acc66ae8aa283fef82e3 Azure: FAILURE

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