[SPEC] Remove state of linked anchors from relayer configs

[drewstone]

(this shouldn't be taken on right now)

Overview

Relayers don't need to store the linked anchor config, instead we can get this information from the edge list of a deployed anchor. The main challenge is to handle dynamic additions to the bridge. The relayer would need to create a new event watcher on the fly if it hasn't set up a watcher for a new addition to an anchor's edge list.

The new anchor addition flow would also required hooking up the AnchorUpdateProposal to the force_submit_unsigned_proposal so that we can get it signed for inclusion into all existing anchors. Finally, we must finish the loop by updating the new anchor with the state of all existing anchors as well.

Checklist

• [ ] Spec a dynamic addition of a new anchor onto an existing bridge
• [ ] Remove configuration and use on-chain
• [ ] Define flow for adding new anchors to an existing bridge
• [ ] Spawn new event watchers when new anchors are added to an existing bridge (and in general)
• [ ] more to spec...