Add "Show thread" button to public profiles (#13000)

This adds "Show thread" button to the status view which is used in
profiles. The logic to display the button is mimicking logic in
web app available at app/javascript/mastodon/components/status.js#L439.

* The little change in components CSS required to remove enforced
  underline for all links on public pages on our button.

config/locales/en.yml

@@ -1088,6 +1088,7 @@ en:
         other: "%{count} votes"
       vote: Vote
     show_more: Show more
+    show_thread: Show thread
     sign_in_to_participate: Sign in to participate in the conversation
     title: '%{name}: "%{quote}"'
     visibilities: