What does this PR do?

This is a first POC. I'm exploring to use nostr not as primary DB but as a cache system of a decentralized network such as the federation of Robosats, right now a client has to directly connect to every single coordinator book to fetch its specific orders.

Centralizing this system would create a single point of failure, so I'm exploring a federation cache network, where the full book is aditioanlly stored and maintained by coordinators, allowing users to initially connect just to 2-3 coordinators. any feedback is welcome 🙂

For now this PR just creates a coordinator relay and sends an event every time a new order is created. The note follows this on going NIP nostr-protocol/nips#1331

As additional win, this will allow Robosats to quickly integrate others' platforms orders with just a single implementation