Add transitions for the lockscreen hosted dream

Add a new KeyguardState for the lockscreen hosted dream, as
the transition animations to/from lockscreen/gone/bouncer are
different from the existing dreaming state. We may also add
animations for the lockscreen hosted dream<->lowlight dream
transition in later changes.
Add Gone->DreamingLockscreenHosted transition ViewModel and set
keyguard alpha to 0 immediately and don't animate the clock when
updating its position during the transition.
When dreaming active, the clock will always be centered.

Bug: b/285062308
Test: atest KeyguardTransitionScenariosTest
Test: atest NotificationPanelViewControllerTest
Change-Id: I6678318b9cbd89d8e47cdd04855c1a592dea5d71