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: I5c59dc5785333c543ef9f5e70faafab5da110bbd
2 files changed