Add headers to XCFramework (#52010)

Summary:
We found out that the XCFramework that is generated in CI is missing the headers.
This is happening because we run the setup script, the responsible to prepare the folder structure with the heaeders in the right place, only in the job that builds the slices. However, the headers are copied by the job that composes the XCFramework.

This change stores the header folder as an artifact in the build job and retrieves it in the compose job, so that the files are available to the XCFramework

## Changelog:
[Internal] -

Pull Request resolved: https://github.com/facebook/react-native/pull/52010

Test Plan:
Check the generated artefact in CI
<img width="292" alt="Screenshot 2025-06-13 at 15 32 02" src="https://github.com/user-attachments/assets/437333da-5848-4657-a9b3-e87fc79c69b2" />

Reviewed By: cortinico

Differential Revision: D76599834

Pulled By: cipolleschi

fbshipit-source-id: 44d74b5f8df545a825ecfe3df2e1898effe41261