Get basic user and group information

Example response

{
  "groups": [
    {
      "id": 1,
      "name": "unleash-e2e-7095756699593281",
      "userCount": 1,
      "rootRole": null
    }
  ],
  "users": [
    {
      "id": 4,
      "name": "unleash-e2e-user2-7095756699593281",
      "email": "unleash-e2e-user2-7095756699593281@test.com",
      "accountType": "User"
    },
    {
      "id": 1,
      "username": "admin",
      "accountType": "User"
    }
  ]
}