Rewrite host GPU abstraction

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

src/util/vulkan_pipeline.h

@@ -0,0 +1,43 @@
+// SPDX-FileCopyrightText: 2019-2023 Connor McLaughlin <stenzek@gmail.com>
+// SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
+
+#include "gpu_device.h"
+#include "vulkan_loader.h"
+
+class VulkanDevice;
+
+class VulkanShader final : public GPUShader
+{
+  friend VulkanDevice;
+
+public:
+  ~VulkanShader() override;
+
+  ALWAYS_INLINE VkShaderModule GetModule() const { return m_module; }
+
+  void SetDebugName(const std::string_view& name) override;
+
+private:
+  VulkanShader(GPUShaderStage stage, VkShaderModule mod);
+
+  VkShaderModule m_module;
+};
+
+class VulkanPipeline final : public GPUPipeline
+{
+  friend VulkanDevice;
+
+public:
+  ~VulkanPipeline() override;
+
+  ALWAYS_INLINE VkPipeline GetPipeline() const { return m_pipeline; }
+  ALWAYS_INLINE Layout GetLayout() const { return m_layout; }
+
+  void SetDebugName(const std::string_view& name) override;
+
+private:
+  VulkanPipeline(VkPipeline pipeline, Layout layout);
+
+  VkPipeline m_pipeline;
+  Layout m_layout;
+};