Wait for discovery end to publish omemo devicelist and bundle

Add sv_ev_connection_features_received for that purpose

tests/unittests/omemo/stub_omemo.c

@@ -59,3 +59,4 @@ void omemo_start_session(const char *const barejid) {}
 void omemo_trust(const char *const jid, const char *const fingerprint_formatted) {}
 void omemo_untrust(const char *const jid, const char *const fingerprint_formatted) {}
 void omemo_devicelist_publish(GList *device_list) {}
+void omemo_publish_crypto_materials(void) {}