fix(node:fs/promises): add missing cp and cpSync

[jaw0r3k]

I dont think the pull request requires any tests
Fixes a bug mentioned in discordjs/discord.js#9810

As author of df062d2 added support for that didnt add it directly to fs/promises

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[bartlomieju]

Thanks for the PR @jaw0r3k! I think it would be useful to have a test that checks for presence of these API - could you add some simple assertions that verify that promises.cp and promises.cpSync actually exist?

[jaw0r3k]

Superseded by #22263