Upgrade django-lasuite to v0.0.19 to benefit from the latest resource server
authentication backend. Thanks @qbey for your work. For my needs, @qbey
refactored the class in #46 on django-lasuite.
Integrate ResourceServerAuthentication in the relevant viewset. The integration
is straightforward since most heavy lifting was done in the external-api viewset
when introducing the service account.
Slightly modify the existing service account authentication backend to defer to
ResourceServerAuthentication if a token is not recognized.
Override user provisioning behavior in ResourceServerBackend: now, a user is
automatically created if missing, based on the 'sub' claim (email is not yet
present in the introspection response). Note: shared/common implementation
currently only retrieves users, failing if the user does not exist.