[RenderEngine] Add Android.bp to RenderEngine

Besides make RenderEngine as static library, this patch also intentionally
moves all header files to public includable directory. The header files will be
structured better in the progress of stripping off GL implementation out of
public interfaces.

BUG: 112585051
Test: Build, flash and do display validation
Change-Id: Ife6e27896a2ccee6a23781a43ebc508e2587eb71