fix: container xcodeproj location resolution

[Vadko]

Summary

Since the xcodeproj location in xcworkspacedata can be under the container: prefix, this needs to be accounted for when resolving its path. This PR fixes the issue in a similar way to how the group: prefix is handled.

Test Plan

This PR includes a unit test to verify that an xcworkspacedata file is processed correctly. I also tested building a real project using the updated CLI changes.

Checklist

• Documentation is up to date.
• Follows commit message convention described in CONTRIBUTING.md.
• For functional changes, my test plan has linked these CLI changes into a local react-native checkout (instructions).