yuzu: Port translation support from Citra

Co-Authored-By: Weiyi Wang <wwylele@gmail.com>

src/yuzu/uisettings.h

@@ -75,6 +75,7 @@ struct Values {
     bool game_dir_deprecated_deepscan;
     QVector<UISettings::GameDir> game_dirs;
     QStringList recent_files;
+    QString language;
 
     QString theme;