Get net open margin position limits

Example response

{
  "netOpenPositionLimits": [
    {
      "enterpriseId": "enterprise-123",
      "currency": "BTC",
      "shortMarginPositionNotionalLimit": {
        "quantity": "1000000",
        "currency": "USD"
      },
      "longMarginPositionNotionalLimit": {
        "quantity": "2000000",
        "currency": "USD"
      }
    }
  ]
}