Show the UMO in the hub mode UI

When media is playing or recommendations are present, the UMO will be
Shown in the grid. Arbitrarily placing after smartspace for now.

Bug: 308638964
Bug: 304584416
Flag: ACONFIG com.android.systemui.communal_hub DEVELOPMENT
Test: atest CommunalMediaRepositoryImplTest CommunalInteractorTest
Change-Id: I5a2c05a5d6e202422e118ba6a172afea5b66f3a2