Implement a new Shader API, which can run custom code on GPU

Add RuntimeShader hidden API, which calculates pixel output with
a fragment shader running on GPU.
Extend ColorFiltersMutateActivity HWUI test to use new API and
show how to animate uniforms on UI thread.

Test: Updated HwAccelerationTest
Change-Id: Ia26e44259b12099924facba250880cbbd9be21c7