[change] Refactor localization APIs

* Control writing direction using 'dir' and 'lang' props.
* Change the compiler output for RTL styles polyfill.
* Export 'useLocaleContext' for working with writing direction context.
* Turn I18nManager into a mock API

packages/babel-plugin-react-native-web/src/moduleMap.js

@@ -67,5 +67,6 @@ module.exports = {
   render: true,
   unmountComponentAtNode: true,
   useColorScheme: true,
+  useLocaleContext: true,
   useWindowDimensions: true
 };