This CL adds a new layout ImageLayout::ColorAttachmentAndShaderRead. We
detect that the same ImageHelper object is used for both sampler and
attachment and will pick this new layout instead of ColorAttachment.

Bug: b/175584609
Change-Id: I2089f59d4dc1ad4de7edab0e067797adcfa9b020
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2749479
Commit-Queue: Charlie Lao <cclao@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>