✨(backend) integrate ResourceServerAuthentication on the external api

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.

.github/workflows/meet.yml

@@ -183,6 +183,10 @@ jobs:
       AWS_S3_ENDPOINT_URL: http://localhost:9000
       AWS_S3_ACCESS_KEY_ID: meet
       AWS_S3_SECRET_ACCESS_KEY: password
+      OIDC_RS_CLIENT_ID: meet
+      OIDC_RS_CLIENT_SECRET: ThisIsAnExampleKeyForDevPurposeOnly
+      OIDC_OP_INTROSPECTION_ENDPOINT: https://oidc.example.com/introspect
+      OIDC_OP_URL: https://oidc.example.com
 
     steps:
       - name: Checkout repository