Refactor JSON templates to be generated with ActiveModelSerializers instead of Rabl (#4090)

app/serializers/rest/notification_serializer.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class REST::NotificationSerializer < ActiveModel::Serializer
+  attributes :id, :type, :created_at
+
+  belongs_to :from_account, key: :account, serializer: REST::AccountSerializer
+  belongs_to :status, if: :status_type?,   serializer: REST::StatusSerializer
+
+  def status_type?
+    [:favourite, :reblog, :mention].include?(object.type)
+  end
+end