Add new communal location for UMO

The communal hub UI is accessed from an edge swipe from either the
lock screen or from on top of the dream. We intend for the UMO to be
visible there if media is playing or has played recently.

Bug: 308638964
Bug: 304584416
Flag: ACONFIG com.android.systemui.communal_hub DEVELOPMENT
Test: atest MediaHierarchyManagerTest
Change-Id: If68dee0d3b56df43e53d7066f9aed1ed2c59afb9