Revert "Revert "Add handler for Move activity (#9629)""

This reverts commit bb96a74637.

app/models/account.rb

@@ -44,6 +44,7 @@
 #  fields                  :jsonb
 #  actor_type              :string
 #  discoverable            :boolean
+#  also_known_as           :string           is an Array
 #
 
 class Account < ApplicationRecord
@@ -232,6 +233,10 @@ class Account < ApplicationRecord
     end
   end
 
+  def also_known_as
+    self[:also_known_as] || []
+  end
+
   def fields
     (self[:fields] || []).map { |f| Field.new(self, f) }
   end