[FLINK-32080][FLIP-306][checkpoint] Restoration of FileMergingSnapshotManager

[ljz2051]

What is the purpose of the change

This pull request introduces the restoration mechanism for FileMergingSnapshotManager. See FLIP-306 for more information.

Brief change log

• Restore and re-register the SegmentFileStateHandles into FileMergingSnapshotManager.

Verifying this change

This change added unit tests (FileMergingSnapshotManagerTestBase#testRestore). And the end-to-end tests will be added after FLIP-306 is almost ready.

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: yes
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? (not applicable)

[flinkbot]

CI report:

• cb656dc Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

[ljz2051]

@Zakelly @fredia @masteryhx Could you please take a look ?

[Zakelly]

Thanks for the update, I left some comments.

[Zakelly]

Thanks for the update! LGTM +1