[FLINK-9961] Add CHR function for table/sql API

[yanghua]

What is the purpose of the change

This pull request add CHR function for table/sql API

Brief change log

• Add CHR function for table/sql API

Verifying this change

This change is already covered by existing tests, such as testChr.

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, Yarn/Mesos, 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)

[yanghua]

cc @sihuazhou @suez1224 can you review this PR?

[yanghua]

Merged into PR #6432 , so close this one.