Creates an incident event functionality

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

{
  "data": {
    "id": "474c3918-0bd7-49d9-81b3-45ef2caefa35",
    "type": "incident_event_functionalities",
    "attributes": {
      "incident_event_id": "77f079b5-d619-42e8-b7a4-1e597f1a1ca4",
      "functionality_id": "cc44159f-043f-4c35-84eb-681662602019",
      "status": "partial_outage"
    }
  }
}