Feature request: update file permissions to enforce read-only files

[luispadron]

The files from swiftpkg repositories should be marked read-only (locked) when creating the repositories. This helps ensure users do not accidentally modify a packages contents.

[cgrindel]

Curious. What is the scenario where they are editing the files? Are folks digging into the external directory and modifying files?

[luispadron]

I imagine it's when using rules_xcodeproj since that makes it a lil easier to view the external files / when viewing external sources and accidentally editing a file