List customers currently assigned to an agent

{
  "success": true,
  "data": {
    "total": 0,
    "page": 0,
    "limit": 0,
    "data": [
      {
        "id": "cus_abc123",
        "identifier": "919876543210",
        "name": "string",
        "waba_id": "string",
        "conversation_status": "OPEN"
      }
    ]
  }
}

{
  "success": false,
  "message": "user not authenticated"
}

{
  "success": false,
  "message": "forbidden"
}

{
  "success": false,
  "message": "Agent not found"
}

{
  "success": false,
  "message": "internal server error"
}