fix: Use hidden project configuration for dependency management

[Johnnei]

Fixes #190

I do wonder how well this works with generated source though, will probably test this first with a few office projects before releasing this.

[Johnnei]

As expected, this does cause a bunch of now missing delegation issues to mimic the compile scope. Might need to do some more mapping to support generated sources properly as well 🤔

[Johnnei]

After a lot of trying and tweaking, I concluded that #160 is essentially impossible without relying on commands to change state in sbt (like sbt-scoverage does) or going back to not having a scapegoat task (like wart-remover).
This change is a compromise, go back to the old style that didn't add the projectConfiguration for the actual task, but add a new hidden one to manage the dependency to avoid leaking it into published artifacts.