Vulkan: Optimize resolve of multisample swapchains * Resolves the multisampled image if the last render pass draws into the default framebuffer. * Added test to check the number of resolves in the optimization subpass (credit: Xinyi He) * Added test to check the number of resolves outside the subpass. * Added disabled test to see if the subpass resolve works. Bug: angleproject:6762 Change-Id: I86a8db3387851ab97d5f7a3d8a0ff26961254c14 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3523062 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Amirali Abdolrashidi <abdolrashidi@google.com>