I'm actually calling this "Reasoned bans" (as it may not just be for scaring people), and configured in the same XML file as #4128. As it's an advanced feature, I think putting CRUD in the UI would be pretty major bloat, and it's nice to configure it next to the automatic bans that will reference it.

I won't have an image field, as the message field will be Comcode, so you can just add it in there. I'll document an example.