Qt: Mouse button binding support

src/duckstation-qt/qthostinterface.h

@@ -104,6 +104,7 @@ public Q_SLOTS:
   void updateInputMap();
   void applyInputProfile(const QString& profile_path);
   void onDisplayWindowKeyEvent(int key, bool pressed);
+  void onDisplayWindowMouseEvent(int button, bool pressed);
   void bootSystem(const SystemBootParameters& params);
   void resumeSystemFromState(const QString& filename, bool boot_on_failure);
   void powerOffSystem();
@@ -206,9 +207,6 @@ private:
 
   std::atomic_bool m_shutdown_flag{false};
 
-  // input key maps, todo hotkeys
-  std::map<int, InputButtonHandler> m_keyboard_input_handlers;
-
   QTimer* m_background_controller_polling_timer = nullptr;
   u32 m_background_controller_polling_enable_count = 0;