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/policies/appeal_policy.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class AppealPolicy < ApplicationPolicy
+  def index?
+    staff?
+  end
+
+  def approve?
+    record.pending? && staff?
+  end
+
+  alias reject? approve?
+end