Refactor formatter (#17828)

* Refactor formatter

* Move custom emoji pre-rendering logic to view helpers

* Move more methods out of Formatter

* Fix code style issues

* Remove Formatter

* Add inline poll options to RSS feeds

* Remove unused helper method

* Fix code style issues

* Various fixes and improvements

* Fix test

app/serializers/rest/status_serializer.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class REST::StatusSerializer < ActiveModel::Serializer
+  include FormattingHelper
+
   attributes :id, :created_at, :in_reply_to_id, :in_reply_to_account_id,
              :sensitive, :spoiler_text, :visibility, :language,
              :uri, :url, :replies_count, :reblogs_count,
@@ -71,7 +73,7 @@ class REST::StatusSerializer < ActiveModel::Serializer
   end
 
   def content
-    Formatter.instance.format(object)
+    status_content_format(object)
   end
 
   def url