lncli: add new profile commands

We add a new 'profile' sub command to lncli to manage pre-defined
configuration profiles for all of lncli's CLI flags.

cmd/lncli/main.go

@@ -307,6 +307,7 @@ func main() {
 		printMacaroonCommand,
 		trackPaymentCommand,
 		versionCommand,
+		profileSubCommand,
 	}
 
 	// Add any extra commands determined by build flags.