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

app/serializers/rest/account_serializer.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+class REST::AccountSerializer < ActiveModel::Serializer
+  include RoutingHelper
+
+  attributes :id, :username, :acct, :display_name, :locked, :created_at,
+             :note, :url, :avatar, :avatar_static, :header, :header_static,
+             :followers_count, :following_count, :statuses_count
+
+  def note
+    Formatter.instance.simplified_format(object)
+  end
+
+  def url
+    TagManager.instance.url_for(object)
+  end
+
+  def avatar
+    full_asset_url(object.avatar_original_url)
+  end
+
+  def avatar_static
+    full_asset_url(object.avatar_static_url)
+  end
+
+  def header
+    full_asset_url(object.header_original_url)
+  end
+
+  def header_static
+    full_asset_url(object.header_static_url)
+  end
+end