Add notifications for statuses deleted by moderators (#17204)

db/migrate/20220116202951_add_deleted_at_index_on_statuses.rb

@@ -0,0 +1,7 @@
+class AddDeletedAtIndexOnStatuses < ActiveRecord::Migration[6.1]
+  disable_ddl_transaction!
+
+  def change
+    add_index :statuses, :deleted_at, where: 'deleted_at IS NOT NULL', algorithm: :concurrently
+  end
+end