Add config for default value for restrict dream to wireless charing

There was a default value for restricting hub to wireless charging, but
no separate config for the dream. These are two separate settings, so
creating one for the dream as well.

Bug: 407768891
Fixed: 407768891
Test: verified manually on device by flipping config locally
Flag: android.service.dreams.dreams_v2
Change-Id: Iad189895796eea4c0ec4ce6e3ae8e8de265b87d8