Rewrite host GPU abstraction

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

src/util/window_info.h

@@ -0,0 +1,42 @@
+// SPDX-FileCopyrightText: 2019-2022 Connor McLaughlin <stenzek@gmail.com>
+// SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
+
+#pragma once
+#include "gpu_texture.h"
+#include "common/types.h"
+
+// Contains the information required to create a graphics context in a window.
+struct WindowInfo
+{
+  enum class Type
+  {
+    Surfaceless,
+    Win32,
+    X11,
+    Wayland,
+    MacOS,
+    Android,
+    Display,
+  };
+
+  Type type = Type::Surfaceless;
+  void* display_connection = nullptr;
+  void* window_handle = nullptr;
+  u32 surface_width = 0;
+  u32 surface_height = 0;
+  float surface_refresh_rate = 0.0f;
+  float surface_scale = 1.0f;
+  GPUTexture::Format surface_format = GPUTexture::Format::Unknown;
+
+  // Needed for macOS.
+#ifdef __APPLE__
+  void* surface_handle = nullptr;
+#endif
+
+  ALWAYS_INLINE bool IsSurfaceless() const { return type == Type::Surfaceless; }
+
+  // Changes the window to be surfaceless (i.e. no handle/size/etc).
+  void SetSurfaceless();
+
+  static bool QueryRefreshRateForWindow(const WindowInfo& wi, float* refresh_rate);
+};