[Vulkan] Remove old Vulkan code, change shaders directory, create empty Vulkan backend

src/xenia/ui/vulkan/vulkan_provider.h

@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2016 Ben Vanik. All rights reserved.                             *
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */
@@ -18,29 +18,18 @@ namespace xe {
 namespace ui {
 namespace vulkan {
 
-class VulkanDevice;
-class VulkanInstance;
-
 class VulkanProvider : public GraphicsProvider {
  public:
-  ~VulkanProvider() override;
-
   static std::unique_ptr<VulkanProvider> Create(Window* main_window);
 
-  VulkanInstance* instance() const { return instance_.get(); }
-  VulkanDevice* device() const { return device_.get(); }
-
   std::unique_ptr<GraphicsContext> CreateContext(
       Window* target_window) override;
   std::unique_ptr<GraphicsContext> CreateOffscreenContext() override;
 
- protected:
+ private:
   explicit VulkanProvider(Window* main_window);
 
   bool Initialize();
-
-  std::unique_ptr<VulkanInstance> instance_;
-  std::unique_ptr<VulkanDevice> device_;
 };
 
 }  // namespace vulkan