Add Developer flag for NotificationsIgnoreRequireInteraction

Allow developers to override this behavior via os://flags.

Bug: 274008212
Change-Id: I151df082fa417907cc383d35cd2659ac4f6eb403
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5385009


Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Auto-Submit: Joel Hockey <joelhockey@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1277106}