Make postprocessing threads interruptable

[adam-abed-abud]

As an improvement to the current code base it would be good to make postprocessing threads use std::jthreads (C++20). This would allow to interrupt/stop threads given certain conditions.

Possible application: postprocessing threads used by the TPG could be interrupted/stopped based on an external condition (e.g. high resource utilization or TP rate too high)