Notification resurfacing implementation

With minimal accompanying test. I don't think it's that feasible to
add more/better tests without being able to mock or otherwise control
the time source, or by thread.sleeping which I don't want to do.

Fix: 266680614
Test: atest SafetyCenterNotificationTest
Change-Id: I54190ba690af0b6f583b03f56e98f4ef513e5798