Controls UI - Better structure/app switching

Implement one subscriber per subscription request. Follow publishers
specs for cancellation/completion. Make sure subscriptions get cleaned
up properly in all cases.

Bug: 151145089
Test: atest ControlsControllerImplTest ControlsBindingControllerImplTest ControlsProviderLifecycleManagerTest
Change-Id: I558a7cbcf34c12dab686a65c5d269408c4f8b6f7