ios: Add icon. (I copied the android xhdpi icon and scaled it to the needed sizes, it's ugly but better than a blank square.)
ios: Include overlays in built app bundles.
     Fix crash if the RetroArch.app/modules directory is missing or has no .dylib files inside.
ios: Consolidate generation of the config file path.
     Add the system directory whenever writing the config file.
     Refresh the config file before loaded a game.