Ban users feature #1909
Description
It would be very useful to have a way to ban users. Thankfully, we have never needed this feature yet, but as Codabench becomes more popular, we will eventually need it.
Once someone is banned, what happens to their submissions and data ? Do we delete everything and mark submissions on the leaderboard as made by a banned user ? Or remove the submissions on the leaderboard too ?
What about forum posts, should the content also be deleted or be kept as is ?
What happens if the user that gets banned has ongoing competitions with no no-administrators ?
We should also have a way for users to report users (either because of forum post content, file name or competition name/description, username, and some other reasons)