Vulkan: Store ImageType in ImageHelper. 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/+/2151170 Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>