Add Deprecation headers on deprecated endpoints (#34262)

Co-authored-by: Damien Mathieu <42@dmathieu.com>

app/controllers/concerns/deprecation_concern.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module DeprecationConcern
+  extend ActiveSupport::Concern
+
+  class_methods do
+    def deprecate_api(date, sunset: nil, **kwargs)
+      deprecation_timestamp = "@#{date.to_datetime.to_i}"
+      sunset = sunset&.to_date&.httpdate
+
+      before_action(**kwargs) do
+        response.headers['Deprecation'] = deprecation_timestamp
+        response.headers['Sunset'] = sunset if sunset
+      end
+    end
+  end
+end