EGL: implement EGL_KHR_mutable_render_buffer Pass render buffer mode change to WindowSurfaceVk. On mode change trigger OUT_OF_DATE. Then in CreateSwapchain, if new mode, set the Presentation mode and the Image count. OffscreenSurfaceVk ignores mode change. Add MUTABLE_RENDER_BUFFER_BIT to GenerateDefaultConfig. Test: dEQP-EGL.functional.mutable_render_buffer.* Bug: angleproject:3966 Change-Id: I7b59708514bcda10f8d45ce5f9528aa840fcccfa Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3171822 Commit-Queue: Brandon Schade <b.schade@samsung.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>