Previously we were using the `ts` of the previous message we sent to the thread. While this did work under some situations, it's not recommended in the Slack API docs, and can lead to some unexpected behavior (e.g. when one of the threaded messages is deleted).
This commit updates our logic to always use Slack's returned `thread_ts`, which represents the thread's parent.
This commit centralizes 'display name' generation into a helper, and updates it to respect core preferences for `enable_names` and `prioritize_username_in_ux`.
We were using the internal UID of the channel in the hint, which would then fail to match any 'channel' configs in Discourse (which use the human-friendly `#channel` format). This was causing automatic threading for transcripts to fail.
This allows for the discourse automation plugin to have a "Send Slack
Message" script.
The script fields are a message, url, and slack channel. This will allow
for a custom slack message to be posted but can link back to an
arbitrary url (hopefully a discourse url) like a list of unanswered
topics instead of strictly only allowing a slack message that links back
to a Discourse Post object.
When notifications about a topic are posted to multiple slack channels, and the Discourse channels are configured to "thread" the notifications, each channel will have a different thread_id. Previously we were only storing a single slack thread id per Discourse topic. This commit fixes that logic, so that threads in different channels are tracked separately.
