Do not allow overriding an intent that is already published

[cameronvoell]

Before this change parallel executing threads could calculate two different payload_hash for the same intent id and the second executing thread could override the first's intent in the DB even though it was already published to the network.

libxmtp/xmtp_mls/src/groups/mls_sync.rs

Lines 980 to 1025 in 4336127

	for intent in intents {
	let result = retry_async!(
	Retry::default(),
	(async {
	self.get_publish_intent_data(provider, &mut openmls_group, &intent)
	.await
	})
	);
	match result {
	Err(err) => {
	tracing::error!(error = %err, "error getting publish intent data {:?}", err);
	if (intent.publish_attempts + 1) as usize >= MAX_INTENT_PUBLISH_ATTEMPTS {
	tracing::error!(
	intent.id,
	intent.kind = %intent.kind,
	inbox_id = self.client.inbox_id(),
	installation_id = %self.client.installation_id(),
	group_id = hex::encode(&self.group_id),
	"intent {} has reached max publish attempts", intent.id);
	// TODO: Eventually clean up errored attempts
	provider
	.conn_ref()
	.set_group_intent_error_and_fail_msg(&intent)?;
	} else {
	provider
	.conn_ref()
	.increment_intent_publish_attempt_count(intent.id)?;
	}
	return Err(err);
	}
	Ok(Some(PublishIntentData {
	payload_to_publish,
	post_commit_action,
	staged_commit,
	})) => {
	let payload_slice = payload_to_publish.as_slice();
	let has_staged_commit = staged_commit.is_some();
	provider.conn_ref().set_group_intent_published(
	intent.id,
	sha256(payload_slice),
	post_commit_action,
	staged_commit,
	openmls_group.epoch().as_u64() as i64,
	)?;

This was causing an intent that was already on the network to be overwritten locally, causing the incoming message to be interpreted as an external message, which would cause the sender of the intent to be forked from the rest of the group, this was shows in tests on the following React Native PRs:

• tentative fork repro test xmtp-react-native#534
• Making fork repro test smaller xmtp-react-native#538

After this change the parallel executing commit messages in React Native do not cause the forked state.

[insipx]

iirc, the change from just ToPublish to ToPublish and Published was because of a different race condition, but I don't remember exactly if it was a real issue, or something just transient that did not effect the user (PR). It seems like maybe a non-issue now

[codabrink]

v nice!