feat: support session window

[lmatz]

Is your feature request related to a problem? Please describe.

https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/operators/windows/#session-windows

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

requested by POC

[lmatz]

no longer an active POC request

[github-actions]

This issue has been open for 60 days with no activity.

If you think it is still relevant today, and needs to be done in the near future, you can comment to update the status, or just manually remove the no-issue-activity label.

You can also confidently close this issue as not planned to keep our backlog clean.
Don't worry if you think the issue is still valuable to continue in the future.
It's searchable and can be reopened when it's time. 😄

[stdrc]

Session window has been available in batch and streaming EOWC mode since #17098. I guess we can close this now, since the general streaming version is not planned.