DolphinQt: Add Triforce tab to main settings window.

Source/Core/DolphinQt/MainWindow.h

@@ -92,6 +92,8 @@ public:
   bool eventFilter(QObject* object, QEvent* event) override;
   QMenu* createPopupMenu() override;
 
+  void ShowTriforceWindow();
+
 signals:
   void ReadOnlyModeChanged(bool read_only);
   void RecordingStatusChanged(bool recording);