Creates an incident event service

curl --request POST \
  --url https://api.rootly.com/v1/events/{incident_event_id}/services \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/vnd.api+json' \
  --data '{
  "data": {
    "type": "incident_event_services",
    "attributes": {
      "incident_event_id": "<string>",
      "service_id": "<string>",
      "status": "operational"
    }
  }
}'

{
  "data": {
    "id": "c63d27e1-07e5-4724-8138-0abfc9e0925f",
    "type": "incident_event_services",
    "attributes": {
      "incident_event_id": "80becd53-5d86-4040-be9c-0df71af925d3",
      "service_id": "15c88ce8-0f5e-4761-a6ae-f32f4da11726",
      "status": "partial_outage"
    }
  }
}