🐛(maildomain) fix domain access creation

During a new domain creation, a call to dimail is made
to create user/allow on dimail side before owner role creation
on our side.
So when user/allow creation on dimain side fails,
the owner role is not created on our side.
Therefore the domain is created but invisible on the user interface.
The user will probably try to create the same domain again
and see the error message 'this domain already exists'.
To avoid this we make sure to create owner role on our side
despite dimail failure and set domain to failed status to retry
later dimail access creation.

src/backend/mailbox_manager/tests/api/mail_domain/test_api_mail_domains_create.py

@@ -122,6 +122,77 @@ def test_api_mail_domains__create_authenticated():
     assert domain.accesses.filter(role="owner", user=user).exists()
 
 
+def test_api_mail_domains__create_authenticated__dimail_failure():
+    """
+    Despite a dimail failure for user and/or allow creation,
+    an authenticated user should be able to create a mail domain
+    and should automatically be added as owner of the newly created domain.
+    """
+    user = core_factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    domain_name = "test.domain.fr"
+
+    with responses.RequestsMock() as rsps:
+        rsps.add(
+            rsps.POST,
+            re.compile(r".*/domains/"),
+            body=str(
+                {
+                    "name": domain_name,
+                }
+            ),
+            status=status.HTTP_201_CREATED,
+            content_type="application/json",
+        )
+        rsps.add(
+            rsps.POST,
+            re.compile(r".*/users/"),
+            body=str(
+                {
+                    "name": "request-user-sub",
+                    "is_admin": "false",
+                    "uuid": "user-uuid-on-dimail",
+                    "perms": [],
+                }
+            ),
+            status=status.HTTP_201_CREATED,
+            content_type="application/json",
+        )
+        rsps.add(
+            rsps.POST,
+            re.compile(r".*/allows/"),
+            body=str({"user": "request-user-sub", "domain": str(domain_name)}),
+            status=status.HTTP_403_FORBIDDEN,
+            content_type="application/json",
+        )
+        response = client.post(
+            "/api/v1.0/mail-domains/",
+            {"name": domain_name, "context": "null", "features": ["webmail"]},
+            format="json",
+        )
+    assert response.status_code == status.HTTP_201_CREATED
+    domain = models.MailDomain.objects.get()
+
+    # response is as expected
+    assert response.json() == {
+        "id": str(domain.id),
+        "name": domain.name,
+        "slug": domain.slug,
+        "status": enums.MailDomainStatusChoices.FAILED,
+        "created_at": domain.created_at.isoformat().replace("+00:00", "Z"),
+        "updated_at": domain.updated_at.isoformat().replace("+00:00", "Z"),
+        "abilities": domain.get_abilities(user),
+    }
+
+    # a new domain with status "failed" is created and authenticated user is the owner
+    assert domain.status == enums.MailDomainStatusChoices.FAILED
+    assert domain.name == domain_name
+    assert domain.accesses.filter(role="owner", user=user).exists()
+
+
 ## SYNC TO DIMAIL
 def test_api_mail_domains__create_dimail_domain(caplog):
     """