Create interface for NotifInterruptStateProvider

Take #2
Original CL disabled HUNs because NotificationAlertingManager was
removed from the StatusBar constructor (but never injected elsewhere;
therefore it was never instantiated).

bcb49947

Test: atest SystemUITests
Bug: 151050224
Bug: 150797570
Change-Id: I601d58bfff4422bd0c52e56ebdb4192ce9a8f880