Start accepting `path` object as `peer` paremeter
The ultimate goal is to have the peer
object aware of the path
used to build them. Especially because path caries useful config.
However a lot of work have to be done before that, and this series do some of it.
The next roadblock will be the fact we don't return the path
object in "pulling" context. (You might notice that this series mostly touches cases involving "pushing".)