Implement Skia pipelines for OpenGL and Vulkan.

Implement Skia pipelines for OpenGL and Vulkan:
base SkiaPipeline, SkiaOpenGLPipeline and SkiaVulkanPipeline.
Write unit tests for SkiaPipeline.

Test: Built and run manually on angler-eng.
Change-Id: Ie02583426cb3547541ad9bf91700602a6163ff58
20 files changed