Add class IntentBroadcaster to rebroadcast intents on USER_UNLOCKED.

This is to have a single point for broadcasting intents that need
to be rebroadcast, and helps rebroadcast them in the right order.

Test: Verified manually through logcat
Bug: 37730013
Change-Id: I5285dc1b96b3f6429e86eaa6b4aee58dfb55ccd1