[TabStripDeclutter] Implement backoff timer for nudge to show.

This adds a nudge timer that blocks the nudge from showing from the service if it is running. It uses a OneShotTimer that is restarted when the observer call to the nudge is shown.

Bug: 365796495
Change-Id: I1a6062d2824d74cfdf3db0810689076f4c5ae608
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5848550
Commit-Queue: Shibalik Mohapatra <shibalik@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Darryl James <dljames@chromium.org>
Reviewed-by: Emily Shack <emshack@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1353504}