✨(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_manager/migrations/0018_maildomain_organization.py

@@ -1,20 +0,0 @@
-# Generated by Django 5.1.5 on 2025-02-10 11:10
-
-import django.db.models.deletion
-from django.db import migrations, models
-
-
-class Migration(migrations.Migration):
-
-    dependencies = [
-        ('core', '0010_team_depth_team_numchild_team_path_and_more'),
-        ('mailbox_manager', '0017_alter_maildomain_status'),
-    ]
-
-    operations = [
-        migrations.AddField(
-            model_name='maildomain',
-            name='organization',
-            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, related_name='mail_domains', to='core.organization'),
-        ),
-    ]

src/backend/mailbox_manager/migrations/0023_mailbox_email_mailbox_last_login_mailbox_password.py

@@ -19,7 +19,7 @@ def fill_dn_email(apps, schema_editor):
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('mailbox_manager', '0020_maildomain_organization'),
+        ('mailbox_manager', '0022_maildomain_organization'),
     ]
 
     operations = [