gh-69405: Add check for idle's help.html to CI

[StanFromIreland]

I expect it to fail till #143718 is merged.

I had to refactor copy_strip to a separate file to avoid having to build Python.

• Issue: Automate creation of idlelib/help.html from Doc/.../idle.html #69405

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📚 Documentation preview 📚: https://cpython-previews--143742.org.readthedocs.build/

🏃 Run preview 🏃: https://github.com/python/cpython/actions/runs/20930506392/job/60140508484?pr=143742

[StanFromIreland]

A downside of how I currently have it is that it need the entire docs job to finish (i.e. it includes waiting for the doc tests), we could have it run earlier by moving it under the docs job (though I don't think that is particularly nice), however since it runs in 7 seconds I think it is a negligible issue.

[StanFromIreland]

@webknjaz could you please take a peek at this?

[hugovk]

Should this new job also be required by "All required checks pass"?

https://github.com/python/cpython/actions/runs/20930506392?pr=143742

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A downside of how I currently have it is that it need the entire docs job to finish (i.e. it includes waiting for the doc tests), we could have it run earlier by moving it under the docs job (though I don't think that is particularly nice), however since it runs in 7 seconds I think it is a negligible issue.

The time isn't a problem, but there's quite a bit of extra complexity and config to achieve this, when it could be ~10 extra lines to add a couple of steps to the existing docs job.

[hugovk]

Could this stay in Lib/idlelib/help.py?

[StanFromIreland]

We would have to build CPython if we want to be able to modify it, that's not particularly fast?

[StanFromIreland]

Should this new job also be required by "All required checks pass"?

Terry asked me to not make it required on the issue.