Implement direct transition from dreaming -> hub

This handles the case where the dream is dismissed via tap by hooking
into the unocclusion remote animation to fade in the glanceable hub
before the dream fades out.

Known issues:
1. Notifications occassionally flicker during the dream -> hub
   transition. Not 100% reproducible, likely a timing issue with when
   the notifications are unhidden due to unocclusion and when they are
   re-hidden due to the animation running.
2. The screen dims when the dream is destroyed, and then brightens again
   when the dream is restarted underneath the hub. A follow-up could be
   to grab a wakelock during the transition to avoid this dimming while
   we are transitioning.

Test: atest SystemUiRoboTests
Bug: 325102385
Flag: ACONFIG com.android.systemui.communal_hub TEAMFOOD
Change-Id: I8859355dddf673c579110952a3a730735df71e1d