Avoid including source map file in app's binary

[fluiddot]

Related PRs:

• https://github.com/wordpress-mobile/WordPress-iOS/pull/22874

Internal ref: pcdRpT-5rI-p2#comment-9518

This PR updates the approach for including the React Native source map when publishing the GBM via the XCFramework. The goal is to avoid including it in the final app's binary. Instead of including the file as an asset in the Xcode project, we'll create a new folder to hold both the bundle and source map independent of the iOS frameworks.

The previous approach was introduced in https://github.com/wordpress-mobile/WordPress-iOS/pull/22862.

To test:

• Observe that the XCFramework artifact is generated properly.
• Follow testing instructions from WP-iOS PR.

PR submission checklist:

• [ ] I have considered adding unit tests where possible.
• [ ] I have considered if this change warrants user-facing release notes more info and have added them to RELEASE-NOTES.txt if necessary.