New rule type when all staff (with certain perm) are offline

[cafestifflered]

If this rule type is used, when all staff with a specific permission are offline, automatically disable chat. When those staff are online, follow the other rules.

Example:

staff-offline:
  type: "staff_offline"

Any players with the permission chatrestrict.bypass.<rulename> will still be able to chat when staff are offline. Could be useful for making sure previously-punished players aren't able to talk if staff aren't around, but all other players can chat freely.