Several issues due to the refactor of granted users and groups on links :

• The modification of nodetypes definition does not allow to migrate old data to new storage
• The granted users/groups are AmetysObject, they should not
• The granted users/groups are stored in multiple nodes named ametys-internal:granted-users as direct children link node. They should be store in multiple nodes named ametys-internal:granted-user under a root node named ametys-internal:granted-users