Add configuration option to filter replies in lists (#9205)

* Add database support for list show-reply preferences

* Add backend support to read and update list-specific show_replies settings

* Add basic UI to set list replies setting

* Add specs for list replies policy

* Switch "cycling" reply policy link to a set of radio inputs

* Capitalize replies_policy strings

* Change radio button design to be consistent with that of the directory explorer

app/controllers/api/v1/lists_controller.rb

@@ -38,6 +38,6 @@ class Api::V1::ListsController < Api::BaseController
   end
 
   def list_params
-    params.permit(:title)
+    params.permit(:title, :replies_policy)
   end
 end