Add "Show thread" button to public profiles (mastodon#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.

app/javascript/styles/mastodon/components.scss

@@ -803,6 +803,7 @@
   background: transparent;
   padding: 0;
   padding-top: 8px;
+  text-decoration: none;
 
   &:hover,
   &:active {

app/views/statuses/_simple_status.html.haml

@@ -41,6 +41,10 @@
   - elsif status.preview_card
     = react_component :card, 'maxDescription': 160, card: ActiveModelSerializers::SerializableResource.new(status.preview_card, serializer: REST::PreviewCardSerializer).as_json
 
+  - if !status.in_reply_to_id.nil? && status.in_reply_to_account_id == status.account.id
+    = link_to ActivityPub::TagManager.instance.url_for(status), class: 'status__content__read-more-button', target: stream_link_target, rel: 'noopener noreferrer' do
+      = t 'statuses.show_thread'
+
   .status__action-bar
     - if status.sharekey.present? && user_signed_in? && @account.id == status.account_id
       = link_to "#{TagManager.instance.url_for(status)}?key=#{status.sharekey}", class: 'status__action-bar-button icon-button', style: 'font-size: 18px; width: 23.1429px; height: 23.1429px; line-height: 23.15px', title: 'Right click or long-press to copy share link with key', target: stream_link_target, rel: 'noopener' do

config/locales/en.yml

@@ -1051,6 +1051,7 @@ en:
     replies_rejected: 'The author is not accepting replies to this roar.'
     kicked: "You do not have the author's permission to reply to this thread."
     show_more: Show more
+    show_thread: Show thread
     sign_in_to_participate: Sign in to participate in the conversation
     title: '%{name}: "%{quote}"'
     visibilities: