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_edit_serializer.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class REST::StatusEditSerializer < ActiveModel::Serializer
+  include FormattingHelper
+
   has_one :account, serializer: REST::AccountSerializer
 
   attributes :content, :spoiler_text, :sensitive, :created_at
@@ -11,7 +13,7 @@ class REST::StatusEditSerializer < ActiveModel::Serializer
   attribute :poll, if: -> { object.poll_options.present? }
 
   def content
-    Formatter.instance.format(object)
+    status_content_format(object)
   end
 
   def poll