If the migration contains a new remote_photo_path migrate all photos of
the old person to this path. If the person was local before, cleanup old
uploaded files of the photos.
closes#8314
This commit introduces support for AccountMigration federation message
receive. It covers the cases when the new home pod for a user is remote
respective to the recepient pod of the message. It also allows to initiate
migration locally by a podmin from the rails console. This will give the
pods a possibility to understand the account migration event on the
federation level and thus future version which will implement migration
will be backward compatible with the pods starting from this commit.
