Vulkan: Add GL_ANGLE_yuv_internal_format extension 1. Add a new extension to support creation of immutable textures with sized internal YUV formats 2. Rename YUV format enums from *_ANGLEX to *_ANGLE 3. Move YUV format enums from angleutils.h to glext_angle.h Bug: angleproject:5773 Change-Id: Ibfe732f4c9a4a536be56481f33e4768f6227c212 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2820153 Commit-Queue: Mohan Maiya <m.maiya@samsung.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>