✨(oidc) add django-oauth-toolkit w/ configuration

This allows to use `people` as an identity provider using
OIDC and local users.
This commit is partial, because it does not manage a way to
create "local" users and the login page is the admin one, which
can't be used for non staff users or login with email.

src/backend/mailbox_oauth2/tests/test_views.py

@@ -0,0 +1,83 @@
+"""Tests for the mailbox_oauth2.views module."""
+
+import datetime
+
+from django.utils import timezone
+
+import pytest
+
+from core import factories as core_factories
+
+from mailbox_manager import factories
+
+pytestmark = pytest.mark.django_db
+
+
+def test_login_view_options(client):
+    """Test the OPTIONS method on the login view."""
+    response = client.options("/api/v1.0/login/")
+
+    assert response.status_code == 200
+    assert response.headers == {
+        "Content-Type": "application/json",
+        "Vary": "Accept, Authorization, origin, Accept-Language, Cookie",
+        "Allow": "POST, OPTIONS",
+        "Content-Length": "209",
+        "X-Frame-Options": "DENY",
+        "Content-Language": "en-us",
+        "X-Content-Type-Options": "nosniff",
+        "Referrer-Policy": "same-origin",
+        "Cross-Origin-Opener-Policy": "same-origin",
+    }
+
+
+def test_login_view_authorize(client):
+    """Test the login view with valid data."""
+    organization = core_factories.OrganizationFactory(with_registration_id=True)
+    domain = factories.MailDomainEnabledFactory(
+        organization=organization, name="example.com"
+    )
+    factories.MailboxEnabledFactory(domain=domain, local_part="user")
+
+    response = client.post(
+        "/api/v1.0/login/", {"email": "user@example.com", "password": "password"}
+    )
+    assert response.status_code == 200
+
+    # assert the user has a session
+    assert not client.session.is_empty()
+    assert client.session.get_expiry_date() < timezone.now() + datetime.timedelta(
+        minutes=1
+    )
+
+    assert response.headers == {
+        "Content-Type": "application/json",
+        "Vary": "Accept, Authorization, Cookie, origin, Accept-Language",
+        "Allow": "POST, OPTIONS",
+        "Content-Length": "36",
+        "X-Frame-Options": "DENY",
+        "Content-Language": "en-us",
+        "X-Content-Type-Options": "nosniff",
+        "Referrer-Policy": "same-origin",
+        "Cross-Origin-Opener-Policy": "same-origin",
+    }
+
+
+@pytest.mark.parametrize(
+    "email, password, status_code, response_json",
+    [
+        ("", "password", 400, {"email": ["This field may not be blank."]}),
+        (
+            "email@test.com",
+            "",
+            400,
+            {"password": ["This field may not be blank."]},
+        ),
+    ],
+)
+def test_login_view_invalid_data(client, email, password, status_code, response_json):
+    """Test the login view with invalid data."""
+    response = client.post("/api/v1.0/login/", {"email": email, "password": password})
+
+    assert response.status_code == status_code
+    assert response.json() == response_json