🔧(backend) configure Authorization Code authentication

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

src/backend/pyproject.toml

@@ -35,7 +35,6 @@ dependencies = [
     "django-storages==1.14.2",
     "django-timezone-field>=5.1",
     "django==5.0.2",
-    "djangorestframework-simplejwt==5.3.0",
     "djangorestframework==3.14.0",
     "drf_spectacular==0.26.5",
     "dockerflow==2022.8.0",
@@ -53,6 +52,7 @@ dependencies = [
     "url-normalize==1.4.3",
     "WeasyPrint>=60.2",
     "whitenoise==6.6.0",
+    "mozilla-django-oidc==4.0.0",
 ]
 
 [project.urls]