Additional hooking feature for phase 2: --test file discovery to include additional file extensions

[cspotcode]

I haven't used node's new --test myself, but a feature request prompted me to look at it.

https://nodejs.org/dist/latest-v18.x/docs/api/test.html#test-runner-execution-model

It looks like node --test subdirectory/ will discover all files within subdirectory/ matching certain naming conventions, and with .js, .cjs, or .mjs file extension.

A suite of customization hooks would want to somehow augment this matching behavior to include .cts, .mts, .tsx, and .jsx, and to exclude .d.ts.

[GeoffreyBooth]

It looks like this is being discussed in nodejs/node#44023. If you don’t mind, can we close this issue and keep the discussion in that one? And based on how that thread eventually resolves, you could open a PR against the README on this repo to add a TODO item for whatever they decide (if the consensus solution is in our scope).