Create an interface to access the two pane state

Create an new interface in the embedding provider,
this interface tells if settings app is in two pane or not.

To access the activity in the content provider, we need to store
the activity reference in the app application layer.

Test: See if two pane state is correct.
Bug: 203763572
Change-Id: Iae2245b84af2683d932f1900df9959dad98370d7