Return a cPanel account’s service proxying setup

Example response

{
  "apiversion": 3,
  "func": "get_service_proxy_backends",
  "module": "ServiceProxy",
  "result": {
    "data": [
      {
        "backend": "example.com",
        "service_group": "Mail"
      }
    ],
    "status": 1
  }
}