List campaigns

{
  "measurementCampaigns": [
    {
      "id": "0123456789abcdef",
      "name": "Brand Campaign Q2",
      "startDate": "2024-03-01",
      "endDate": "2024-03-01",
      "customEvents": [
        {
          "id": 1,
          "label": "Signup",
          "pattern": "example.com/sign_up"
        }
      ],
      "pixel": {
        "id": "0123456789abcdef",
        "name": "Attribution Pixel",
        "brand": {
          "crmBrandId": "brand_0123456789abcdef",
          "name": "ACME Corp., Inc.",
          "domain": "acme.com"
        }
      }
    }
  ],
  "meta": {
    "pagination": {
      "currentPage": 1,
      "totalPages": 3,
      "count": 25
    }
  }
}