Add script to prepare the .build folder to prebuild React Native with SwiftPM (#51195)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/51195

This change adds a script that prepares the repository by creating hard links to the header files in the `.build` folder that is also gitignored

## Changelog:
[Internal] - Add sdcript to setup the repository so that we can build it properly.

Test Plan:
run:
```
node packages/react-native/scripts/ios-prebuilds.js
```
observe the folder `.build` being created with all the files.

Reviewed By: cortinico

Differential Revision: D74393116

Pulled By: cipolleschi

fbshipit-source-id: 4951e61b49db83fbebbcc265ae025f53185fec81