SurfaceFlinger: Prepare to remove BufferQueueLayer

To prepare to remove BufferQueueLayer we port over the public Java API
(getSurface) and a few remaining clients (largely tests), by returning
a BBQ from getSurface.

Bug: 185492007
Test: Existing tests pass
Change-Id: I0ec0d765659783e1bdbb3f243ad60e3355cfdf4f
13 files changed