xmpp: Do not bounce result IQs

lib/xmpp/iq.dart

@@ -2,7 +2,7 @@ import 'package:moxxyv2/xmpp/connection.dart';
 import 'package:moxxyv2/xmpp/stanza.dart';
 
 bool handleUnhandledStanza(XmppConnection conn, Stanza stanza) {
-  if (stanza.type != 'error') {
+  if (stanza.type != 'error' && stanza.type != 'result') {
     conn.sendStanza(stanza.errorReply('cancel', 'feature-not-implemented'));
   }