Support for enforcing thread affinity

[WardLT]

Is your feature request related to a problem? Please describe.
Multi-threaded applications can interfere with each other if you run >1 per node.

Describe the solution you'd like
Port/allow access to Parsl's CPU affinity support.

Describe alternatives you've considered
Baking thread affinity into the functions being run.

[WardLT]

I can see benefits of ~10x with thread pinning for some problems, enough to make me think using SSH tunnels and Parsl are worth it.