If depth/stencil is not loaded, and it's not written to during the
render pass, then treat it as if it was invalidated so storeOp can be
set to DONT_CARE and its corresponding resolve attachment (if any)
removed.

This is especially useful for MSRTT as a resolve attachment is added at
the start of render pass, and this optimization will give it a chance to
undo that if depth/stencil was not actually used in the render pass.

This situation can arise for example if a render pass is created for the
sole purpose of clearing color.

This change includes a bug fix for missing depth/stencil on*Access in
the UtilsVk blit/resolve path.

Bug: angleproject:4836
Change-Id: Ifc8eea3e6ffb3eb4bba19f03d1358f151ec69c44
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2453468Reviewed-by: Charlie Lao <cclao@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>