This patch concerns the Telegram integration. Currently, we always try
to process commands when we receive a hook from Telegram. To do so we
rely on the `text` parameters from a Telegram message but the
API documentation tells us this parameters is actually optional. It
means sometimes it’s not present in the payload we receive but we still
try to access it resulting in a crash.
This patch addresses the issue by simply returning early from the
`#process_command` method when `text` is missing from the payload since
we don’t have anything to process then.
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.
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.
