Reopens a terminated contract job (BF-7527).

Undoes POST /terminate the way the "Open Job" button in Bilflo does. A closed job (terminated and past its end date) is made Approved and active again, its end date is cleared, its first week-ending date becomes the first week-end on or after reopenDate, the contractor is made active again, and the missing timecards from that week through next week are created. reopenDate is required and cannot be before the job start date or a past termination date. A job terminated with a future date that has not closed yet only has its end date removed; reopenDate is ignored and nothing else changes. 400 when the job is not terminated, the date is invalid, or the company plan has no room for another active contract job.