Add RAIntegration event handler

Some refactoring done to hardcore toggling so that it's more readily available for the toggle hardcore event.

Source/Core/DolphinQt/Settings.h

@@ -222,7 +222,6 @@ signals:
   void SDCardInsertionChanged(bool inserted);
   void USBKeyboardConnectionChanged(bool connected);
   void EnableGfxModsChanged(bool enabled);
-  void HardcoreStateChanged();
 
 private:
   Settings();