[FLINK-35964][table] Add the built-in function STARTSWITH & ENDSWITH

[dylanhz]

What is the purpose of the change

Add the built-in function STARTSWITH & ENDSWITH.
Examples:

> SELECT STARTSWITH('SparkSQL', 'Spark');
 TRUE
> SELECT STARTSWITH('SparkSQL', 'spark');
 FALSE

> SELECT ENDSWITH('SparkSQL', 'SQL');
 TRUE
> SELECT ENDSWITH('SparkSQL', 'sql');
 FALSE

Brief change log

FLINK-35964
FLINK-35965

Verifying this change

StringFunctionsITCase#startsWithTestCases
StringFunctionsITCase#endsWithTestCases

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): (yes)
• 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? (yes)
• If yes, how is the feature documented? (docs)

[flinkbot]

CI report:

• 1ddf02b Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

[lincoln-lil]

Only minor comments for the 1st commit.

[dylanhz]

@flinkbot run azure

[lincoln-lil]

@flinkbot run azure

[lincoln-lil]

The failed case LeftOuterJoinTaskTest#testCancelLeftOuterJoinTaskWhileBuilding in core moulde looks weird...

[lincoln-lil]

@dylanhz thanks for your updates! LGTM