Add escalation status widget to incidents in GraphQL

What does this MR do and why?

Add escalation status widget to incidents in GraphQL (#631726)

To migrate incidents to work item incidents, we need feature parity. We need to add incident-only widgets to work items so that when we view incidents in the work item detail view we can also see the incident widgets

References

• #631726

Screenshots or screen recordings

How to set up and validate locally

1. Test that the escalation status is returned for an incident

query{
  namespace(fullPath:"flightjs/Flight") {
    workItem(iid:"60"){
      widgets {
        ... on WorkItemWidgetEscalationStatus {
          type
          escalationStatus
        }
      }
    }
  }
}

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Related to #631726