Allow the dream activity in SLS.

We should not have to explicitly allowlist dreams, as any developer
should be able to make a dream and have it run on the device.

Test: locally on device
Test: atest FrameworksMockingServicesTests:CommunalManagerServiceTest
Bug: 203673428
Bug: 203692863
Bug: 203684016
Change-Id: I932b6574dcfc29826554ee058dbcee161503e03c