Méthode d'auth + SSO

doc/source/administrator/authentification.md

doc/source/administrator/authentification/ad.md

doc/source/administrator/authentification/index.rst

doc/source/administrator/authentification/local_user.md

doc/source/administrator/authentification/sso.md

doc/source/administrator/index.rst

...ges/administrator/authentification/oidc_checkbox_user.png

...es/administrator/authentification/sequence_oidc_vitis.jpg