Support tracking whether the aggregation window or group is changed

[yl-lisen]

Use case

Choose a good way to track whether the aggregation window or group changes, which can be used in:

• emit changelog for aggregated result (supported, but there are some bugs)
• only emit changed windows (TODO)
• only emit changed groups (TODO)
• incremental checkpointing (TODO)

Describe the solution you'd like

Describe alternatives you've considered

Additional context

[jovezhong]

(Jove Github Bot) assuming it is not done, deferred this ticket to the next sprint.

[jovezhong]

(Jove Github Bot) assuming it is not done, deferred this ticket to the next sprint.

[jovezhong]

(Jove Github Bot) assuming it is not done, deferred this ticket to the next sprint.