[FLINK-36664][Window]Window with offset need deal offset when cal nextTriggerWatermark.

[xing1mo]

What is the purpose of the change

Fixed the problem of data loss in window with offset.

Brief change log

Passing in window offset when cal nextTriggerWatermark.

Verifying this change

This change added tests and can be verified as follows:

• Added test that validates that widow data with offset is not lost.

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:

• f5816a2 Azure: SUCCESS

Bot commands

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

[xing1mo]

@xuyangzhong Dear xuyang, could you please review it for me when you have some time? Thank you!