Vulkan: Move image layout into helper. Now that we're using the helper everywhere, we can clean up the vk::Image class and move the layout tracking into ImageHelper. Bug: angleproject:2318 Change-Id: I9636835a2a3a76f181dac629bd4182bc5815cdee Reviewed-on: https://chromium-review.googlesource.com/980774 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Frank Henigman <fjhenigman@chromium.org>