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

db/migrate/20220210153119_add_overruled_at_to_account_warnings.rb

@@ -0,0 +1,5 @@
+class AddOverruledAtToAccountWarnings < ActiveRecord::Migration[6.1]
+  def change
+    add_column :account_warnings, :overruled_at, :datetime
+  end
+end