main: Open folder when open save folder location context menu is clicked

src/citra_qt/main.h

@@ -105,6 +105,7 @@ private slots:
     void OnStopGame();
     /// Called whenever a user selects a game in the game list widget.
     void OnGameListLoadFile(QString game_path);
+    void OnGameListOpenSaveFolder(u64 program_id);
     void OnMenuLoadFile();
     void OnMenuLoadSymbolMap();
     /// Called whenever a user selects the "File->Select Game List Root" menu item