fix(ios): app display name being null
fix(ios): app display name being null

since `CFBundleDisplayName` can be null on some cases, so `getAppName`
will return `CFBunldeName` in those cases

rebeccahughes/react-native-device-info,rebeccahughes/react-native-device-info,rebeccahughes/react-native-device-info,rebeccahughes/react-native-device-info,rebeccahughes/react-native-device-info,rebeccahughes/react-native-device-info