debounce/Time without emission on complete

[backbone87]

It would be nice if an option could be added to the debounce/Time operators to control the "emit on complete" behavior.

• debounceTime(1000, { emitOnComplete: 'immediate' }): default behavior, same as current implementation
• debounceTime(1000, { emitOnComplete: 'discard' }): complete downstream without emission of a potentially buffered value
• debounceTime(1000, { emitOnComplete: 'debounce' }): await the normal debounce timeout, if there is a value buffered, then emit and complete

edit: I know I can use takeUntil downstream, but that would require multicasting or passing around a signal controller pattern
edit2: would also be useful on audit/Time operators