add timeout based on process_time (cpu time) for machine learning

[bitranox]

introduce timeout based on cpu_time for machine learning workloads, ensuring that parameter optimizations terminate below pre-defined timeout.
This eliminates sensitivity to any other workload happening on the same host.
This would ensure that the optimization step is independent of other processes using the host.

the plan is to add a parameter use_process_time which defauls to False to use wallclock time.
if that parameter is set to True we use process_time

proposed by @cyber42