Renderer: Change SetBlendState to accept a BlendingState

This decouples the state generation (from the emulated GPU) from the
management of internal backend state.

Source/Core/VideoBackends/D3D/Render.cpp

@@ -640,11 +640,9 @@ void Renderer::ReinterpretPixelData(unsigned int convtype)
                                    FramebufferManager::GetEFBDepthTexture()->GetDSV());
 }
 
-void Renderer::SetBlendMode(bool forceUpdate)
+void Renderer::SetBlendingState(const BlendingState& state)
 {
-  BlendingState state;
-  state.Generate(bpmem);
-  gx_state.blend.hex = state.hex;
+  s_gx_state.blend.hex = state.hex;
 }
 
 // This function has the final picture. We adjust the aspect ratio here.

Source/Core/VideoBackends/D3D/Render.h

@@ -19,7 +19,7 @@ public:
   Renderer();
   ~Renderer() override;
 
-  void SetBlendMode(bool forceUpdate) override;
+  void SetBlendingState(const BlendingState& state) override;
   void SetScissorRect(const EFBRectangle& rc) override;
   void SetGenerationMode() override;
   void SetDepthMode() override;