Add appeals (#17364)

* Add appeals

* Add ability to reject appeals and ability to browse pending appeals in admin UI

* Add strikes to account page in settings

* Various fixes and improvements

- Add separate notification setting for appeals, separate from reports
- Fix style of links in report/strike header
- Change approving an appeal to not restore statuses (due to federation complexities)
- Change style of successfully appealed strikes on account settings page
- Change account settings page to only show unappealed or recently appealed strikes

* Change appealed_at to overruled_at

* Fix missing method error

app/models/account.rb

@@ -270,6 +270,10 @@ class Account < ApplicationRecord
     true
   end
 
+  def previous_strikes_count
+    strikes.where(overruled_at: nil).count
+  end
+
   def keypair
     @keypair ||= OpenSSL::PKey::RSA.new(private_key || public_key)
   end