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": "f079edf1-f03f-4df1-8593-25f5dba8555a",
    "type": "incident_event_functionalities",
    "attributes": {
      "incident_event_id": "ba9bf693-7a99-4a54-b792-76811a339a37",
      "functionality_id": "32dac20f-3748-4383-9ed6-aa216a2739b9",
      "status": "partial_outage"
    }
  }
}