It would be nice if a project admin could turn off comments on an individual ticket basis. I believe this should be possible with our permission backend, we just need a UI for removing 'POST' and 'UNMODERATED_POST' on the individual artifact. The "mark as private" checkbox does similar for the 'READ' permission.
We should also include it in solr so that it is possible to search by it (e.g. discussion_closed: true/false
)
ready for review: hs/7850
Cleaned up a bit more and merged it.