Set or clear a trading account's display nickname.

{
  "code": null,
  "data": {
    "account_id": "b2e571d1-54b6-42a5-a09a-ccd543594567",
    "nickname": "NQ Runner"
  },
  "error": null,
  "success": true
}

{
  "code": "ERROR_CODE",
  "data": null,
  "error": "Error message describing what went wrong",
  "success": false
}

{
  "code": "ERROR_CODE",
  "data": null,
  "error": "Error message describing what went wrong",
  "success": false
}

{
  "code": "ERROR_CODE",
  "data": null,
  "error": "Error message describing what went wrong",
  "success": false
}