Add function to sign XCFramework (#49863)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/49863

After the creation of the XCFramework, that needs to be signed. After the XCFramework is signed, no further modification can happen or they would break the signature.

## Changelog:
[Internal] - Add function to sign the XCFramework

Reviewed By: cortinico

Differential Revision: D70697279

fbshipit-source-id: c2411ca7d12d4679ba55f124cbb445367b15945a