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": "d6df225c-9770-43f3-9398-697a7b322bdf",
    "type": "incident_event_functionalities",
    "attributes": {
      "incident_event_id": "0110b7d2-2afe-4750-b873-6396ac9b1834",
      "functionality_id": "cb70f81f-3072-4f7f-a5f6-eb645e7f57b7",
      "status": "partial_outage"
    }
  }
}