[FLINK-22484][table] Add built-in MAP_KEYS, MAP_VALUES, MAP_FROM_ARRA…

[snuyanzin]

What is the purpose of the change

The PR implements three functions from the list mentioned in FLINK-22484 : MAP_KEYS, MAP_VALUES, MAP_FROM_ARRAYS

Brief change log

Implementation, tests and docs for MAP_KEYS, MAP_VALUES, MAP_FROM_ARRAYS

Verifying this change

This change added tests and can be verified as follows:

• CollectionFunctionsITCase

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/Mesos, 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 / JavaDocs

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Automated Checks

Last check on commit dd83582 (Fri May 28 11:09:16 UTC 2021)

Warnings:

• No documentation files were touched! Remember to keep the Flink docs up to date!
• This pull request references an unassigned Jira ticket. According to the code contribution guide, tickets need to be assigned before starting with the implementation work.

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Review Progress

• ❓ 1. The [description] looks good.
• ❓ 2. There is [consensus] that the contribution should go into to Flink.
• ❓ 3. Needs [attention] from.
• ❓ 4. The change fits into the overall [architecture].
• ❓ 5. Overall code [quality] is good.

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CI report:

• 46d2d65 Azure: SUCCESS

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[twalthr]

Thanks for the PR @snuyanzin. Let me know if you have questions.

[MartijnVisser]

@snuyanzin Does it make sense to restart/rework this PR?

[snuyanzin]

several times i felt lack of that feature...
probably you're right i should give it another chance

[liuyongvs]

@snuyanzin do you rework it again. if you do not have time,I can do it

[snuyanzin]

@MartijnVisser (I tag you since you've recently asked about this)
the PR is rebased, let's wait for the feedback

[liuyongvs]

It looks good to me. and i left one minor comments

[snuyanzin]

rebased to resolve conflicts