allow using `overrides.properties` while generating repositories

[RangerRick]

This PR adds support for using overrides.properties when using the features-add-to-repository mojo. This allows you to generate a repository that doesn't contain extraneous bundles that won't be used anyway.

I have provided test coverage for the different cases I ran into while working on this, it should be fairly complete. That said, I'd appreciate feedback on anything I can change or improve.