daemon: add --public-node mode, RPC port propagation over P2P

src/cryptonote_protocol/cryptonote_protocol_handler.inl

@@ -231,6 +231,7 @@ namespace cryptonote
         cnx.ip = cnx.host;
         cnx.port = std::to_string(cntxt.m_remote_address.as<epee::net_utils::ipv4_network_address>().port());
       }
+      cnx.rpc_port = cntxt.m_rpc_port;
 
       std::stringstream peer_id_str;
       peer_id_str << std::hex << std::setw(16) << peer_id;