user: add helper to add role to user (#52226)

Mainly for tests.

src/authentic2/custom_user/models.py

@@ -629,6 +629,14 @@ class User(AbstractBaseUser):
                 self.email_verified = False
                 self.email_verified_date = None
 
+    def add_role(self, role, ou=None):
+        from authentic2.a2_rbac.models import Role
+
+        if isinstance(role, Role):
+            role.members.add(self)
+        elif isinstance(role, str):
+            Role.objects.get(name=role).members.add(self)
+
 
 class DeletedUser(models.Model):
     deleted = models.DateTimeField(verbose_name=_('Deletion date'), auto_now_add=True)