Force the nick name to be unique with a DB constraint, with an issue
where the user name for the OLAT token is the auto generated identity
name after changing the password

REST add a user search by external id, remove the login value of UserVO
if identity name are automatically generated

Login happens only with authentication informations, identity name is
now only used for legacy directory name. User name of authentication can
be changed. LDAP users can be imported with LDAP::ldapUid. Users can be
imported in courses, groups... with First name last name.

Hide the SMS phone number in lists and forms, disable the buttons to
change it if the property is read-only, add an option to define if the
user is asked or not for SMS phone number at login

Implement relation between identities with a configurable role,
administration to manage the roles, and the relations in user
management.