Modify savelayer to save matrix and clip for Skia pipeline

Modify SkiaCanvas::saveLayer to always save matrix and clip and
match HWUI behaviour. Also ensure android state tracking
behavior matches that of the Skia API (partial saves not
supported). This change is fixing SaveLayerAnimation
macrobench when buffer age is disabled.
Add a HWUI unit test that verifies clip and matrix are restored.

Test: built and ran angler-eng, ran hwui unit tests
bug:33429678
Change-Id: I62e429f9746518fef67663b0dd99ac499bf31af3