[FLINK-39479][python] Add fromChangelog() to Python Table API

[raminqaf]

What is the purpose of the change

The Python Table API is missing the Table.fromChangelog() method introduced with the changelog PTFs (FLIP-564).

Brief change log

  - Add from_changelog() to pyflink/table/table.py
  - Remove fromChangelog from completeness test exclusions

Verifying this change

• Completeness check for python doesn't fail anymore

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 / comments)

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[flinkbot]

CI report:

• 972ea23 Azure: SUCCESS

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[Au-Miner]

Currently, both the from_changelog and to_changelog lack corresponding Python side tests, and have even been enlarged to include insert_into and print_explain in the entire table.py. I think we can create a Jira to fill in this part of the testing.

[twalthr]

Make sense. Overall Python is only forwarding to Java, so we did not always adds tests for the conversion. If the file syntactically compiles there is a high chance that also a test should pass.

[raminqaf]

@Au-Miner Thanks for pointing this out. Added a new ticket so we can track this: https://issues.apache.org/jira/browse/FLINK-39505

[gustavodemorais]

Thanks for addressing the feedback, @raminqaf. LGTM