test: exit sequence sanity tests

Execute many module loads in worker in a loop while exiting from the main thread at arbitrary execution points, and make sure that the workers quiesce without crashing.

worker_threads are not necessarily the subject of testing, those are used for easy simulation of multi-thread scenarios.

Refs: https://github.com/nodejs/node/issues/25007

The current code base is not yet ready to conceive this, so please don't land this before #25007 (closed) is fully resolved.

Checklist

• tests and/or benchmarks are included
• commit message follows commit guidelines