gh-126927: Add functools.retry decorator function

[jude253]

Past PR: #126928

NEW PR NOTE: I added updates to the past PR that I raised such as formatting the code and adding news/whats new. I do not have time at the moment to have a discussion about adding this feature, so I will mark this PR as a draft, then update the description and publish this review after.

I added a retry decorator to functools, written in pure python so it should be maximally portable. I also added unit tests covering all aspects of the functionality. This is something I have been wishing to have for years and I explain in this issue: #126927

It has some keyword arguments that can be configured for different retry behavior and smart defaults.

This is my first contribution to CPython and I would really appreciate any feedback or pointers to add this change.

Tests

• I ran ./python -m unittest Lib/test/test_functools.py -v with no errors
  • I ensured that the new tests I wrote work
• I ran make patchcheck successfully

• Issue: Add retry function to Python standard library #126927

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📚 Documentation preview 📚: https://cpython-previews--126943.org.readthedocs.build/

[skirpichev]

Closes on same ground as #126928

[jude253]

Ok, I will first re-open the issue after creating a discussion, then I will create a PR. Sorry I don't fully understand the workflow, yet!

[skirpichev]

Ok, I will first re-open the issue after creating a discussion

Just mention someone from triage team in the issue. But after your proposal will get some support on the https://discuss.python.org/.