Spec language for ANGLE_external_objects_flags
Spec language for ANGLE_external_objects_flags

This extension will allow the application to specify create and usage
flags used to create a Vulkan image that is being imported in GL.

Bug: angleproject:4912
Bug: fuchsia:52759
Change-Id: I635e87eaf8bb0797e474dd91b11d4b3779e9a3f3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2335018
Commit-Queue: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>
Reviewed-by: Michael Spang <e1fb1a05abba8fb04acbcbe6d766da7764320db0@chromium.org>
Reviewed-by: Kenneth Russell <1ebccd90c2bc76de65b6f830f2128a91ed69fdfb@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle