If I have a processing time timer, is there any way to automatically set the output timestamp to the timer firing timestamp (similar to how event-time timers work).
A common use case would be to do something like: timer.offset(X).align(Y).setRelative() but have the output timestamp be the firing timestamp. In order to do this now you need to re-calculate the output timestamp (using the same logic as the timer does internally) and manually use withOutputTimestamp. I'm not sure what the API would look like here, but it would also be nice to allow event-time timers to do the same in reverse (use the element input timestamp rather than the firing timestamp). Maybe something like `withDefaultOutputTimestampFrom(...)` and an enum of FIRING_TIMESTAMP, ELEMENT_TIMESTAMP?
