Renderer: Add a base Initialize() method to match Shutdown()

Source/Core/VideoCommon/RenderBase.cpp

@@ -93,6 +93,11 @@ Renderer::Renderer(int backbuffer_width, int backbuffer_height)
 
 Renderer::~Renderer() = default;
 
+bool Renderer::Initialize()
+{
+  return true;
+}
+
 void Renderer::Shutdown()
 {
   // First stop any framedumping, which might need to dump the last xfb frame. This process

Source/Core/VideoCommon/RenderBase.h

@@ -79,6 +79,9 @@ public:
 
   virtual bool IsHeadless() const = 0;
 
+  virtual bool Initialize();
+  virtual void Shutdown();
+
   virtual void SetPipeline(const AbstractPipeline* pipeline) {}
   virtual void SetScissorRect(const MathUtil::Rectangle<int>& rc) {}
   virtual void SetTexture(u32 index, const AbstractTexture* texture) {}
@@ -188,8 +191,6 @@ public:
 
   virtual std::unique_ptr<VideoCommon::AsyncShaderCompiler> CreateAsyncShaderCompiler();
 
-  virtual void Shutdown();
-
   // Drawing utility shaders.
   virtual void DrawUtilityPipeline(const void* uniforms, u32 uniforms_size, const void* vertices,
                                    u32 vertex_stride, u32 num_vertices)