Add a handshake to the coordinator LibP2p proccess

[kayabaNerve]

Not only do we want one to ensure only validators join the network, we want to ensure all nodes on a coordinator network are running the same protocol version/network.

[kayabaNerve]

Coordinators could self-declare the networks they service in order to inform who they're connecting to what they're usable for (though these claims should be authenticated by the validator keys signed with).