Fix RN 0.48+ warning about requiresMainQueueSetup
Fix RN 0.48+ warning about requiresMainQueueSetup

Warning: Module RNI18n requires main queue setup since it overrides constantsToExport but doesn't implement `requiresMainQueueSetup. In a future release React Native will default to initializing all native modules on a background thread unless explicitly opted-out of.
AlexanderZaytsev/react-native-i18n,AlexanderZaytsev/react-native-i18n,AlexanderZaytsev/react-native-i18n,AlexanderZaytsev/react-native-i18n