Consolidate occlusion events into KeyguardStateController

Use KeyguardStateController as the source of truth for occlusion. Make
sure events get triggered when occlusion changes as well as showing
states.

Fixes: 226626262
Test: atest CentralSurfacesTest StatusBarKeyguardViewManagerTest
Change-Id: I01a9e802c8bfffea98df12d6876c536a4f6134aa