Create a realm 'impress' and configure it to support
the authorization code flow.

Integrate 'mozilla-django-oidc' dependency, to support
Authorization Code flow, which is required by Agent Connect.

Thus, we provide a secure back channel OIDC flow, and return
to the client only a session cookie.

Done:
- Replace JWT authentication by Session based authentication in DRF
- Update Django settings to make OIDC configurations easily editable
- Add 'mozilla-django-oidc' routes to our router
- Implement a custom Django Authentication class to adapt
'mozilla-django-oidc' to our needs

'mozilla-django-oidc' routes added are:
- /authenticate
- /callback (the redirect_uri called back by the Idp)
- /logout

Force login to bypass authorization checks when necessary.

Note: Generating a session cookie through OIDC flow
is not supported while testing our API.

Found typos and fixed them.

The local deployment of the Production image through docker-compose was
failing due to issues in the Django configurations, influenced by Joanie.

The bug stemmed from a dependency on a development-specific package
(drf-spectacular-sidecar) while attempting to run the application in
production mode.

Changes Made:
- Introduced new Django settings for local demo environments.

Add tests on get_or_create method.

Lint backend tests and sources.