👔(backend) object user on DocumentAccessSerializer

user field was displaying the userid, but we
need to return the user object on the
DocumentAccessSerializer, so we can show the
user email on the frontend.
We add the user_id field in write_only mode, so
we can keep create and update.

src/backend/core/models.py

@@ -289,6 +289,7 @@ class BaseAccess(BaseModel):
         return {
             "destroy": can_delete,
             "update": bool(set_role_to),
+            "partial_update": bool(set_role_to),
             "retrieve": bool(roles),
             "set_role_to": set_role_to,
         }