doc: adds mjs examples to node:child_process

[mfdebian]

I've added mjs examples for the child_process documentation.

I've tested every single example (except for the Windows ones because I don't own a Windows machine ☹️) on my machine and they all work/behave as expected.

I've refrained from making any changes to the cjs examples except for the one in child_process.fork(modulePath[, args][, options]) where the require statement was inside a condition. I took the liberty to put the require statement at the top of the example; If you don't like that I can revert that change.

Thanks in advance for all your hard work, I hope this PRs are helpful 😊 (and not bothersome 🙈)

Best regards ❤️

[RedYetiDev]

Duplicate of #53616

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Sorry! I know you put time and effort into making this, and I know it must be upsetting for that to go unused. Don't worry, every line matters :-)

[mfdebian]

@RedYetiDev Thank you! no worries, it me who should've checked before doing it, I'm going to be more precise in investigating before committing to a PR, thanks for the feedback 🫶 it's greatly appreciated!