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
PR-URL: https://github.com/nodejs/node/pull/25083


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>