Add lang attribute to withdrawal notice

Withdrawal notices are always presented in English but sometimes
appear on a translated page. This passes en as a language value to
the notice component when that happens.

app/presenters/content_item/withdrawable.rb

@@ -9,11 +9,13 @@ def page_title
     end
 
     def withdrawal_notice_component
+      I18n.locale.to_s == "en" ? lang = false : lang = "en"
       if withdrawn?
         {
           title: withdrawal_notice_title,
           description_govspeak: withdrawal_notice["explanation"]&.html_safe,
           time: withdrawal_notice_time,
+          lang: lang
         }
       end
     end