Stub Vulkan backend support

A lot of the architecture of the emulator here does not allow for vulkan
to initialize easily since it involves a bit of data to be exchanged
between SDL and Vulkan. This commit just adds the foundational linkage
and library code for vulkan support.

include/renderer_vk/renderer_vk.hpp

@@ -0,0 +1,18 @@
+#include "renderer.hpp"
+#include "vulkan_api.hpp"
+
+class GPU;
+
+class RendererVK final : public Renderer {
+  public:
+	RendererVK(GPU& gpu, const std::array<u32, regNum>& internalRegs);
+	~RendererVK() override;
+
+	void reset() override;
+	void display() override;
+	void initGraphicsContext() override;
+	void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) override;
+	void displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) override;
+	void drawVertices(PICA::PrimType primType, std::span<const PICA::Vertex> vertices) override;
+	void screenshot(const std::string& name) override;
+};

include/renderer_vk/vulkan_api.hpp

@@ -0,0 +1,10 @@
+#pragma once
+
+#define VK_NO_PROTOTYPES
+#include <vulkan/vulkan.h>
+
+#define VULKAN_HPP_DISPATCH_LOADER_DYNAMIC 1
+#define VULKAN_HPP_NO_EXCEPTIONS
+#include <vulkan/vulkan.hpp>
+#include <vulkan/vulkan_format_traits.hpp>
+#include <vulkan/vulkan_hash.hpp>