Turn parent dates from subtasks on or off for a project

The project's default for a task with subtasks; a task's own isManual (PUT /tasks/{id}) wins over it. Off moves nothing. On, while the server switch parent_date_rollup_enabled is on, sets every automatic parent's dates to its subtasks' span at once and answers the moves; while the switch is off the value is stored, applied is false and nothing moves. While on, a date, duration or constraint change on an automatic parent is refused with 409 PARENT_DATES_FROM_SUBTASKS. Setting the current value is a no-op. Needs the same access as Recalculate.