Add expo config plugin

[alextoudic]

Summary

This PR introduces an Expo config plugin that enables setting supported locales for both iOS and Android directly from the app config. This is necessary to properly support Expo CNG while taking advantage of app language settings, as explained in the README.

How it works

• iOS: Sets the CFBundleLocalizations key in the app’s Info.plist
• Android: Generates a locale_config.xml file following the Android per-app language configuration guide

Screen record
https://github.com/user-attachments/assets/7c778f90-9fb9-45db-86be-6323997526cc

Test Plan

What's required for testing (prerequisites)?

Find example app on https://github.com/alextoudic/react-native-localize/tree/expo-plugin-demo/expo-example

What are the steps to test it (after prerequisites)?

Run example app

Compatibility

OS	Implemented
iOS	✅
Android	✅

Checklist

• I have tested this on a device and a simulator
• I added the documentation in README.md
• I added a sample use of the API in the example project (example/src/App.js)

[zoontek]

Thank you! I merged it to cleaning it up: 9dc5c2b
I will release it once it's ready.

[zoontek]

@alextoudic Final version is here: https://github.com/zoontek/react-native-localize/blob/master/src/expo.ts
Released in v3.5.0