Profile redirect notes (#5746)

* Serialize moved accounts into REST and ActivityPub APIs

* Parse federated moved accounts from ActivityPub

* Add note about moved accounts to public profiles

* Add moved account message to web UI

* Fix code style issues

app/serializers/activitypub/actor_serializer.rb

@@ -10,6 +10,8 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
 
   has_one :public_key, serializer: ActivityPub::PublicKeySerializer
 
+  attribute :moved_to, if: :moved?
+
   class EndpointsSerializer < ActiveModel::Serializer
     include RoutingHelper
 
@@ -25,6 +27,8 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
   has_one :icon,  serializer: ActivityPub::ImageSerializer, if: :avatar_exists?
   has_one :image, serializer: ActivityPub::ImageSerializer, if: :header_exists?
 
+  delegate :moved?, to: :object
+
   def id
     account_url(object)
   end
@@ -92,4 +96,8 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
   def manually_approves_followers
     object.locked
   end
+
+  def moved_to
+    ActivityPub::TagManager.instance.uri_for(object.moved_to_account)
+  end
 end

app/serializers/rest/account_serializer.rb

@@ -7,6 +7,10 @@ class REST::AccountSerializer < ActiveModel::Serializer
              :note, :url, :avatar, :avatar_static, :header, :header_static,
              :followers_count, :following_count, :statuses_count
 
+  has_one :moved_to_account, key: :moved, serializer: REST::AccountSerializer, if: :moved?
+
+  delegate :moved?, to: :object
+
   def id
     object.id.to_s
   end