Add a collect manifest plugin

Work on this was originally started by Valentin David here: https://gitlab.com/freedesktop-sdk/freedesktop-sdk/tree/valentindavid/experimental-manifest to solve freedesktop-sdk/freedesktop-sdk#376 (closed)

I have extended this to support patch/source detection.

This is part of freedesktop-sdk/freedesktop-sdk#376 (closed)