Integrate relay into peer conn

- extend mgm with relay address
- extend signaling with remote peer's relay address
- start setup relay connection before engine start

signal/client/client.go

@@ -51,8 +51,7 @@ func UnMarshalCredential(msg *proto.Message) (*Credential, error) {
 }
 
 // MarshalCredential marshal a Credential instance and returns a Message object
-func MarshalCredential(myKey wgtypes.Key, myPort int, remoteKey wgtypes.Key, credential *Credential, t proto.Body_Type,
-	rosenpassPubKey []byte, rosenpassAddr string) (*proto.Message, error) {
+func MarshalCredential(myKey wgtypes.Key, myPort int, remoteKey wgtypes.Key, credential *Credential, t proto.Body_Type, rosenpassPubKey []byte, rosenpassAddr string, relaySrvAddress string) (*proto.Message, error) {
 	return &proto.Message{
 		Key:       myKey.PublicKey().String(),
 		RemoteKey: remoteKey.String(),
@@ -65,6 +64,7 @@ func MarshalCredential(myKey wgtypes.Key, myPort int, remoteKey wgtypes.Key, cre
 				RosenpassPubKey:     rosenpassPubKey,
 				RosenpassServerAddr: rosenpassAddr,
 			},
+			RelayServerAddress: relaySrvAddress,
 		},
 	}, nil
 }