List service accounts

{
  "serviceAccounts": [
    {
      "id": "string",
      "label": "string",
      "description": "string",
      "createdAt": "2019-08-24T14:15:22Z"
    }
  ]
}

{
  "error": "string"
}

{
  "error": "string"
}

{
  "error": "string"
}