Addition of a new end2end test to verify that all
supported formats can be overridden for the
GL_EXT_texture_sRGB_override extension.

Bug: angleproject:4561
Test: angle_end2end_tests
       --gtest_filter=SRGBTextureTestES3.SRGBOverrideFormats*Vulkan*
Change-Id: I93c4eab0489a1daadeb27c70ba1f755ed2e58fc4
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2483564Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>