MAM: Add nbxmpp properties to event

Fixes #9876

gajim/common/modules/mam.py

@@ -245,6 +245,7 @@ def _mam_message_received(self, _con, stanza, properties):
              'message': stanza,
              'stanza': stanza,
              'namespace': properties.mam.namespace,
+             'properties': properties,
              })
 
         app.logger.insert_into_logs(self._account,