Add Dark theme, Icon theming

configure_general.ui: Add UI Option for Themes

config.cpp: Save Theme Settings

src/yuzu/main.h

@@ -166,6 +166,9 @@ private:
 
     QAction* actions_recent_files[max_recent_files_item];
 
+    // stores default icon theme search paths for the platform
+    QStringList default_theme_paths;
+
 protected:
     void dropEvent(QDropEvent* event) override;
     void dragEnterEvent(QDragEnterEvent* event) override;