Add support for Ycbcr Conversion Samplers in vulkan.

The only thing missing from this CL is that we need to bake the
ycbcr conversion samplers into the VkPipeline when we create it. As that
is a larger change, that will be broken up into a few follow on CLs.

Currently this only supports ycbcr conversion samplers when used with
external textures.

Bug: skia:
Change-Id: I23e95b19469093072589ebbbfb7926ab79dcdea9
Reviewed-on: https://skia-review.googlesource.com/c/164602
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
25 files changed