Worker Thread Investigation

[ColbyTresness]

Tracking item for the investigation into worker threads, which have been introduced in Node 12. We're not sure how much this will help relative to some other changes we've been planning on making (multiple worker processes, principally).

Let's build a POC with worker threads and do some preliminary performance testing.

[fabiocav]

Changing priority assignment.

[mhoeger]

Effectively addressed by https://docs.microsoft.com/en-us/azure/azure-functions/functions-app-settings#functions_worker_process_count, although perhaps needs more investigation