OAuth2 authentication

[frafra]

We use LDAP for internal services, and OAuth2 (using Feide) for external services. Since the catalog is an external service, I thought to use OAuth2, locking the access to NINA users for the moment: we can consider later opening it to specific external users or partners.

[nicokant]

https://docs.allauth.org/en/latest/socialaccount/providers/openid.html