Transitions - Make them cancelable

Data layer - Add 'isKeyguardGoingAway' information, allow transitions
to be cancelable and add in Cancel state.

Domain layer - Listen for state transitions and then attempt to
cancel/interrupt them under the right circumstances, such as when the
power button is pressed in the middle of an aod -> lockscreen
transition.

Bouncer fixes - hide() was never called when using the back gesture,
resulting in incorrect bouncer state.

Test: atest KeyguardTransitionRepositoryTest
KeyguardRepositoryImplTest KeyguardBouncerTest BouncerInteractorTest
Bug: 195430376

Change-Id: Id1b79253ab6334e8e5941c89e94e267126b08ecb