Add a new schedule

Example request

{
  "start": "2022-02-02T22:00",
  "end": "2022-04-02T22:00",
  "build_start": "2022-02-02T22:00",
  "build_end": "2022-04-02T22:00",
  "assignment_id": 12,
  "host_id": 1
}