List supported exchanges

{
  "success": true,
  "data": {
    "exchanges": [
      {
        "id": "string",
        "name": "string",
        "capabilities": {
          "ohlcv": true,
          "ticker": true,
          "placeOrder": true,
          "cancelOrder": true,
          "cancelAllOrders": true,
          "positions": true,
          "setLeverage": true,
          "fetchBalance": true,
          "stopLossOrders": true,
          "takeProfitOrders": true
        },
        "hasTestnet": true,
        "credentialFields": [
          {
            "key": "string",
            "label": "string",
            "required": true
          }
        ]
      }
    ],
    "total": 0
  },
  "meta": {
    "timestamp": 0,
    "remaining": 0
  }
}