Implement a way to tell if an IP address is a known relay

For the DoS mitigation subsystem (#24902 (moved)), we need a way to lookup the connection address and quickly know if it is a known relay or not. This is also needed for #2667 (moved) which would prevent Exit to reenter the network.

nickm has started a branch to have IP addresses with bloom filter: address_set_029.

Next step is to use that and bridge it with the nodelist so we can lookup an IP address and learn if it is known or not (not get the node_t back, that would require more work and probably lose in performance).