Abuse report: use mjolnir ban lists rather than banning in just the reported room

Currently the report system only carries out bans etc in the single room from the report

It would be great if instead if it was possible to configure it to add the ban to a ban list so that the action would be applied to all protected rooms

Start at the report system's handling of bans and other moderation actions, then trace how protected rooms and ban lists are configured. The change is complete when a configured report action adds the ban to a Mjolnir ban list and the action applies across all protected rooms.

Written by the indexing model from the issue text.