Move mSurfaceFlingerConsumer into BufferLayer

One of the benefits of splitting the Layer class to
have the BufferLayer specific derived class is so
that the SurfaceFlingerConsumer can be completely
removed from the ColorLayer class (which has no
BufferQueue).   This change implements that change.

Test: Transaction_test.cpp and manual test

Change-Id: Ia923c3e0ea366f58de61eca31b444b3332a23e51