🐛 rename yarn for yarn-v4 and add run cmpl

[AucaCoyan]

Heya!

This yarn file is aimed at the latest yarn v4, which has different commands than yarn classic (v1)

I renamed the file to make that difference

custom-completions/yarn/yarn-completion.nu
#to
custom-completions/yarn/yarn-v4-completions.nu

and also added an improvement on yarn run which I have on pnpm, changing this

into this

(note that the new yarn adds the binaries in addition to the package.json scripts values)

[fdncred]

This is a breaking change but probably a good one as it provides more information on which yarn it requires. Thanks!