Follow normal workflow for OMEMO message reception

We try to decrypt all messages, if it's successful we use
sv_ev_incoming_message even for OMEMO messages. We pass an OMEMO
boolean to let UI be aware that message were encrypted.

src/xmpp/omemo.h

@@ -8,3 +8,4 @@ void omemo_devicelist_request(const char * const jid);
 void omemo_bundle_publish(void);
 void omemo_bundle_request(const char * const jid, uint32_t device_id, ProfIqCallback func, ProfIqFreeCallback free_func, void *userdata);
 int omemo_start_device_session_handle_bundle(xmpp_stanza_t *const stanza, void *const userdata);
+char * omemo_receive_message(xmpp_stanza_t *const stanza);