[FLINK-37184][connector/filesystem] Add ZStandard to supported standard decompressors

[JoeryH]

What is the purpose of the change

• Support ZStandard decompression for input files of the new File API. When ZStandard was first added it was only added to the old File API, the new File API was left out.

Brief change log

• Added ZStandard to the list of decompressors in StandardDeCompressors

Verifying this change

• Added unit test for StandardDeCompressors

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): no
• 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? no
• If yes, how is the feature documented? not applicable

[flinkbot]

CI report:

• 3ee951c Azure: FAILURE

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[davidradl]

2 thoughts:

• I think there should be a unit test for this
• It would be useful to document these decompressors and how this effects the API.

[davidradl]

Please can you supply a unit test to that makes use of this change.

[davidradl]

Reviewed by Chi on 23/01/2025 Go back to the submitter with review comments.

[JoeryH]

@davidradl Thanks for looking at my PR. I'll add some sort of unit test tomorrow, if you have anything specific in mind, please let me know.

On the documentation I wholeheartedly agree. But I am pretty new to Flink and I don't know how to change the documentation or really even what to document. I'm still a little bit confused about the status of https://cwiki.apache.org/confluence/display/FLINK/FLIP-27%3A+Refactor+Source+Interface. It's been quite a while, but the old API has better support for compressions: it has zstd added and it has an API to register more compressions for Flink users, while the new API has neither.

[JoeryH]

@davidradl I added an unit test