Fraud proof communication

What is the current direction this is headed? I'm not sure how bad payloads are supposed to be communicated between `mev-boost` nodes and I think this is important in order to know ahead of time which relays to avoid using.

The options I can think of are:
1. consensus layer p2p - seems like the best solution but not feasible pre-merge
2. `mev-boost` implements p2p - also seems unlikely pre-merge, but maybe with re-use of Prysm's libraries this wouldn't actually be too bad
3. relays are used to also relay fraud proofs, and this would rely on relays policing each other. Their incentive for doing this is to increase their own flow of payloads by notifying `mev-boost` nodes that *other* relays are misbehaving. This one seems least appealing but maybe the easiest to actually implement pre-merge. Relevant comment: https://github.com/flashbots/mev-boost/pull/82#issuecomment-1091851969