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": "be79ae2b-5470-491e-affb-977f55ce2bd2",
    "type": "incident_event_functionalities",
    "attributes": {
      "incident_event_id": "b3531106-41f8-4df9-b12a-b9f8f6613b75",
      "functionality_id": "d531f12d-5012-4a50-807a-5e8b950b1096",
      "status": "partial_outage"
    }
  }
}