[FLINK-30452][hive] fix use wrong argument type of null literal is used when call Hive's function

[luoyuxia]

What is the purpose of the change

To wrong argument type is used when it's null literal while calling Hive's function

Brief change log

When it's null literal, consider it as WritableVoidObjectInspector instead of WritableConstantStringObjectInspector.

Verifying this change

Added test testNullLiteralAsArgument

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[flinkbot]

CI report:

• a0101dd Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[beyond1920]

LGTM, thanks for contribution.
I would merge asap.