Add support for GL_EXT_copy_image which allows
image data transfer between image objects.
This is implemented by using the vkCmdCopyImage
API call.

Bug: angleproject:3593
Test: dEQP-GLES31.functional.copy_image.*
Change-Id: I30a34a8711b5d2e5834064d7453e03d6ec0df478
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2393955
Commit-Queue: Brandon Schade <b.schade@samsung.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>