Vulkan: Move image clear functionality to UtilsVk DispatchUtilsVk is renamed to UtilsVk and the functionality in framebuffer's clearWithDraw() is moved to that class. Eventually, more fragment-shader-based internal algorithms will be added to this class as well. Bug: angleproject:2958 Change-Id: I4753c9cb3288b59cd1ed60fe7a57b9f189704322 Reviewed-on: https://chromium-review.googlesource.com/c/1369284 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>