Tuist is becoming better and better by the day!

This PR supports making use of Package.swift files to define dependencies to better align with SPM while still keeping tuist's optimisations!

https://github.com/tuist/tuist/pull/5503

As an indication of how badly this project has degraded my mental state, I at some point managed to create a file in the project directory named ":wq". Either you understand this post or you don't.