Rewrite host GPU abstraction

- Don't have to repeat the same thing for 4 renderers.
 - Add native Metal renderer.

src/util/platform_misc.h

@@ -1,8 +1,6 @@
 // SPDX-FileCopyrightText: 2019-2022 Connor McLaughlin <stenzek@gmail.com>
 // SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
 
-#include "common/window_info.h"
-
 namespace FrontendCommon {
 void SuspendScreensaver();
 void ResumeScreensaver();