Multithread executor example

Hello! I had read the [examples](https://github.com/robosoft-ai/SMACC2/tree/humble/smacc2_sm_reference_library), however I could not find one using the multithread executor.
https://github.com/robosoft-ai/SMACC2/blob/16053db8f2436944b263418c86bccbdffa73ffca/smacc2/src/smacc2/signal_detector.cpp#L364

How to use multithread executor and callbackgroups with SMACC2?