test: allow recursive testing

[RedYetiDev]

Blocks #52875

This PR gives the test runner support for recursive searching for test files. This is being backported, as in #52875 (and similar future PRs), testing will (hopefully) be moved to subdirectories.

[RedYetiDev]

@nodejs/testing
@nodejs/backporters

[RedYetiDev]

By the way, this PR should be backported to 18 and 20, I'm not sure if the labels I applied are correct.

[RedYetiDev]

Thanks @richardlau, I'm new to backporting. For the future, what would be the appropriate labels?

[richardlau]

Possibly lts-watch-*, although strictly speaking it shouldn't be necessary for a release line in active LTS (e.g. 20.x).

Refer to https://github.com/nodejs/node/blob/main/doc/contributing/backporting-to-release-lines.md

[RedYetiDev]

Possibly lts-watch-*, although strictly speaking it shouldn't be necessary for a release line in active LTS (e.g. 20.x).

Refer to main/doc/contributing/backporting-to-release-lines.md

Okay, thanks. Should I add lts-watch for 18 and 20? This change should be the exact same for the other lines, as I don't think the files that this is editing have changed.

[RedYetiDev]

@targos, is there anything in particular I need to do for the backport?

[targos]

As @richardlau suggested: add lts-watch-* labels.