Add a way to configure multithreading options for all tasks

[lorenzomammana]

Description & Motivation

Right now we have no direct way to setup the number of threads used by numpy or torch, as such there are cases of heavy cpu usage for certain operations causing issues to multple users environments.

It would be nice to have a way to set the standard multithreading environment variables OMP_NUM_THREADS OPENBLAS_NUM_THREADS MKL_NUM_THREADS VECLIB_MAXIMUM_THREADS NUMEXPR_NUM_THREADS

And torch num threads