Make the discovery of jid type more reliable for MUCs

XEP-0045 requires a room to
- have an identity with category='conference'
- advertise support for the 'http://jabber.org/protocol/muc' feature

Thus it is more reliable to check for both of these things.

Monal/Classes/xmpp.m

@@ -4485,7 +4485,8 @@ -(AnyPromise*) checkJidType:(NSString*) jid
             //the "account" jidType makes it possible to add the component as a contact.
             if([identities containsObject:@"account"])
                 return resolve(@"account");
-            else if([features containsObject:@"http://jabber.org/protocol/muc"])
+            else if([identities containsObject:@"conference"]
+                   && [features containsObject:@"http://jabber.org/protocol/muc"])
                 return resolve(@"muc");
             else
                 return resolve(@"account");