multi: thread anchor client down to wtclient subserver

lnrpc/wtclientrpc/config.go

@@ -19,6 +19,10 @@ type Config struct {
 	// through the watchtower RPC subserver.
 	Client wtclient.Client
 
+	// AnchorClient is the backing watchtower client for anchor channels that
+	// we'll interact through the watchtower RPC subserver.
+	AnchorClient wtclient.Client
+
 	// Resolver is a custom resolver that will be used to resolve watchtower
 	// addresses to ensure we don't leak any information when running over
 	// non-clear networks, e.g. Tor, etc.