EPIC: Full Mesh Overlay

[evan-forbes]

In order to decrease the number of hops required to distribute votes and block data, a full mesh network can be overlay where validators only communicate with each other. There is a strict requirement that this is not a simple replacement of the p2p stack. We only want to send specific data over this network.

• Add the ability to only send data directly instead of always gossiping it #1480
• Add the ability to maintain a list of peers that are validators #1481
• Add the ability for validators to authenticate themselves over the p2p stack #1482
• Add the ability to gossip only other validator ips #1483
• FMO ADR #1490
• FMO Spec #1491