Merge #3006

3006: p2p local root peers r=dcoutts a=dcoutts

First parts of integrating the new scheme for local root peers.

This changes to the new representation but does not yet introduce the governor targets of the local root peers being established or active peers. That'll be in follow-up patches (either extending this PR or after).

I have those changes locally, but they need rebasing and tidying up. This is what I have ready to merge so far.

Co-authored-by: Duncan Coutts <duncan@well-typed.com>
Co-authored-by: Armando Santos <armando@well-typed.com>
Co-authored-by: Armando Santos <armandoifsantos@gmail.com>