Run AddSpecialCaseCopies in HloRematerialization.

RemoveUnnecessaryCopies which runs in rematerialization to take advantage of scheduling can sometimes remove copies which are needed to non-interference reasons. This requires running AddSpecialCaseCopies to add them back in. Furthermore, the schedule needs to be updated to account for the changes to the module, so add an UpdateSchedule function which can patch up a schedule in light a limited set of transformations to the module (addition and deletion of instructions).

PiperOrigin-RevId: 210186375