[FLINK-35030][runtime] Introduce Epoch Manager under async execution

[fredia]

What is the purpose of the change

This PR introduces Epoch Manager to handle watermark and watermark status processing under async execution. Epoch manager segments inputs into distinct epochs, marked by the arrival of non-records(e.g.watermark, record attributes). Records are assigned to a unique epoch based on their arrival, records within an epoch are allowed to be parallelized, while the non-record of an epoch can only be executed when all records in this epoch have finished.

Brief change log

• Add SerialEpochManager and ParallelEpochManager
• Wire SerialEpochManager to AEC
• Leverage EpochManager to process watermark/watermark status

Verifying this change

This change added tests and can be verified as follows:

• EpochManagerTest
• AsyncExecutionControllerTest#testSerialEpochManager

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): (yes)
• 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? (JavaDocs)

[flinkbot]

CI report:

• 41cd07d407c8b7a24107af5b80883d358e9a7dc8 Azure: SUCCESS

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

[fredia]

Thanks all for the detailed review! 🚀🚀