Query network params over local protocol

With the current setup, the node, explorer (and in future the wallet) all need a configuration (which includes the network magic), the genesis file, and the genesis hash. The then connect via the client-to-node protocol the node and client validate that everything is correct.

It would *FAR* nicer if the node/explorer/wallet could be completely ignorant of all this stuff and just connect to the node and retrieve this information over the client-to-node protocol. The client has to trust the local node anyway.

This would only be added to the client-to-node protocol and not the node-to-node one.

Highest priority first:
* Network magic
* Genesis hash
* Genesis distribution UTxO set (maybe).