Publish `check_docs.ts` script as a package

[marvinhagemeister]

Is your feature request related to a problem? Please describe.

Recently the Fresh CI broke because the checksum of https://github.com/denoland/std/blob/main/_tools/check_docs.ts changed, see https://github.com/denoland/fresh/actions/runs/17701967986/job/50308802072?pr=3425

Describe the solution you'd like

Since this script is popular among our repositories we should publish it as a proper package instead.

Describe alternatives you've considered

[WasixXD]

Maybe publishing the whole _tools folder as a package could be beneficial, as it contains plenty of useful scripts.

[iuioiua]

Maybe publishing the whole _tools folder as a package could be beneficial, as it contains plenty of useful scripts.

I agree.

Also related #6649