multi: add labels to lnd native transactions

Follow up labelling of external transactions with labels for the
transaction types we create within lnd. Since these labels will live
a life of string matching, a version number and rigid format is added
so that string matching is less painful. We start out with channel ID,
where available, and a transaction "type". External labels, added in a
previous PR, are not updated to this new versioned label because they
are not lnd-initiated transactions. Label matching can check this case,
then check for a version number.

server.go

@@ -971,8 +971,11 @@ func newServer(cfg *Config, listenAddrs []net.Addr, chanDB *channeldb.DB,
 		IDKey:              nodeKeyECDH.PubKey(),
 		Wallet:             cc.wallet,
 		PublishTransaction: cc.wallet.PublishTransaction,
-		Notifier:           cc.chainNotifier,
-		FeeEstimator:       cc.feeEstimator,
+		UpdateLabel: func(hash chainhash.Hash, label string) error {
+			return cc.wallet.LabelTransaction(hash, label, true)
+		},
+		Notifier:     cc.chainNotifier,
+		FeeEstimator: cc.feeEstimator,
 		SignMessage: func(pubKey *btcec.PublicKey,
 			msg []byte) (input.Signature, error) {