Mjolnir features to incorporate

[Gnuxie]

• Notify moderation room when users in protected rooms mention the bot (configurable) matrix-org/mjolnir#553:
  We will have to rewrite this as a protection in order to incorporate it.
• Don't allow mods to demote bot or members of management room in protected rooms matrix-org/mjolnir#555:
  Needs further thought and discussion, mainly need to consider removing stale admins.
  For now, it would be a good idea to demote draupnir before leaving on rooms remove.
• Don't shut down protected rooms matrix-org/mjolnir#554:
  Probably cover by upgrading the command to --no-confirm and a better preview.
• Add a test verifying messageIsMediaProtection matrix-org/mjolnir#545:
  This can probably be done easily.
• Don't ban users in moderator room matrix-org/mjolnir#544:
  Some progress has already been made here in Improve the information we have about the management room. #610. We would just need to inject the check into the capabilities we give to protections.
• Add native encryption support to Mjolnir matrix-org/mjolnir#528:
  We already have this feature, the annoying part is the differences in Mjolnir and Draupnir's config. Our own version of this feature is also lacking documentation. Element have broken compatibility here.
• Support authenticated media (by updating bot-sdk / matrix-appservice-bridge) matrix-org/mjolnir#523:
  We didn't upgrade the bot-sdk yet but it will probably be uneventful to do so.
• Enhance media protections matrix-org/mjolnir#516:
  No comment
• Use spoilers when mentioning targets of a rule matrix-org/mjolnir#559:
  Easy enough to update the PolicyChangeNotification protection, but we will also need to add the spoiler tag to @the-draupnir-project/interface-manager if it doesn't exist already.