Update status embeds (#4742)

- Use statuses controller for embeds instead of stream entries controller
- Prefer /@:username/:id/embed URL for embeds
- Use /@:username as author_url in OEmbed
- Add follow link to embeds which opens web intent in new window
- Use redis cache in development
- Cache entire embed

app/views/stream_entries/_detailed_status.html.haml

@@ -1,4 +1,9 @@
 .detailed-status.light
+  - if embedded_view?
+    = link_to "web+mastodon://follow?uri=#{status.account.local_username_and_domain}", class: 'button button-secondary logo-button', target: '_new' do
+      = render file: Rails.root.join('app', 'javascript', 'images', 'logo.svg')
+      = t('accounts.follow')
+
   = link_to TagManager.instance.url_for(status.account), class: 'detailed-status__display-name p-author h-card', target: stream_link_target, rel: 'noopener' do
     %div
       .avatar

app/views/stream_entries/embed.html.haml

@@ -1,2 +1,3 @@
-.activity-stream.activity-stream-headless
-  = render @type, @type.to_sym => @stream_entry.activity, centered: true
+- cache @stream_entry.activity do
+  .activity-stream.activity-stream-headless
+    = render "stream_entries/#{@type}", @type.to_sym => @stream_entry.activity, centered: true