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": "38d61f74-68f5-4826-893c-7fb4bc80d25d",
    "type": "incident_event_functionalities",
    "attributes": {
      "incident_event_id": "56daeb81-63f1-4bbd-bfa5-e7516fe873d2",
      "functionality_id": "70fd77be-75a0-4f13-9697-8245a7ce598c",
      "status": "partial_outage"
    }
  }
}