Add moderator role and add pundit policies for admin actions (#5635)

* Add moderator role and add pundit policies for admin actions

* Add rake task for turning user into mod and revoking it again

* Fix handling of unauthorized exception

* Deliver new report e-mails to staff, not just admins

* Add promote/demote to admin UI, hide some actions conditionally

* Fix unused i18n

config/i18n-tasks.yml

@@ -46,6 +46,7 @@ ignore_missing:
   - 'terms.body_html'
   - 'application_mailer.salutation'
   - 'errors.500'
+
 ignore_unused:
   - 'activemodel.errors.*'
   - 'activerecord.attributes.*'
@@ -58,3 +59,4 @@ ignore_unused:
   - 'errors.messages.*'
   - 'activerecord.errors.models.doorkeeper/*'
   - 'errors.429'
+  - 'admin.accounts.roles.*'