Revert "ERP5Security.ERP5LoginUserManager: enumerateUsers() should not include Persons without any Login."

This reverts commit caefbddd.

patches/DCWorkflow: use 'user/getIdOrUserName' as workflow actor expression instead of 'user/getId'.

so that ID is used for ERP5 user case, that should never change, and User Name is used for system users
like Anonymous User or System Processes, without changing all workflow definitions.

This transition is now available when Person has no validated Login document.
Person's reference is now set only when it is not yet set.

Before it raised an exception if called with id=(A, B) where A has Login and B has no Login.