Fix recent apps in system UI for Skia pipeline

Enable HW Bitmaps for Skia pipelines by using a readback to
convert GraphicBuffer into a raster SkImage. Both BitmapShader
and drawing HW bitmaps into a canvas are supported.

Test: recent apps work, no memory leaks, CTS graphics and
UiRendering tests passed, HWUI unit test passed
bug: 38136140
Change-Id: I23fed5febad3b1009e0417fb7e21a347a8d11b0d
Merged-In: I23fed5febad3b1009e0417fb7e21a347a8d11b0d