We ended up needing this to recover the image type in the RenderTarget.
Otherwise we don't have direct access to this information in the
FramebufferVk sync state code.

Bug: angleproject:4517
Change-Id: I387947e0b7394e1f63f313dd4792bb042b8da73a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2151170Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Charlie Lao <cclao@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>