Consider refactor example chapter16_08 with preemptive OS and idle-task

[ckormanyos]

The purpose of this issue is to consider refactoring example chapter16_08 to use a preemptive OS and perform the Miller-Rabin calculation within its perpetual, yet interruptable, low-priority idle-task.

[ckormanyos]

OK. Example chapter11_07, which has the FreeRTOS template stamp for this adaption) has been upgraded and is now ready. See also #588.