Move controller creation to System class, switch shared_ptr to unique_ptr

src/duckstation/sdl_host_interface.h

@@ -13,8 +13,6 @@
 #include <mutex>
 
 class System;
-class DigitalController;
-class MemoryCard;
 class AudioStream;
 
 class SDLHostInterface final : public HostInterface
@@ -33,9 +31,6 @@ public:
 
   void Run();
 
-protected:
-  void ConnectControllers() override;
-
 private:
   static constexpr u32 NUM_QUICK_SAVE_STATES = 10;
   static constexpr char RESUME_SAVESTATE_FILENAME[] = "savestate_resume.bin";
@@ -98,8 +93,6 @@ private:
 
   std::map<int, SDL_GameController*> m_sdl_controllers;
 
-  std::shared_ptr<DigitalController> m_controller;
-
   u32 m_switch_gpu_renderer_event_id = 0;
 
   bool m_quit_request = false;