Villalva Algorithm Pull Request

[JFrederico2022]

• Closes #xxxx
• I am familiar with the contributing guidelines
• I attest that all AI-generated material has been vetted for accuracy and is in compliance with the pvlib license
• Tests added
• Updates entries in docs/sphinx/source/reference for API changes.
• Adds description and name entries in the appropriate "what's new" file in docs/sphinx/source/whatsnew for all changes. Includes link to the GitHub Issue with :issue:`num` or this Pull Request with :pull:`num`. Includes contributor name and/or GitHub username (link with :ghuser:`user`).
• New code is fully documented. Includes numpydoc compliant docstrings, examples, and comments where necessary.
• Pull request is nearly complete and ready for detailed review.
• Maintainer: Appropriate GitHub Labels (including remote-data) and Milestone are assigned to the Pull Request and linked Issue.

[github-actions]

Hey @JFrederico2022! 🎉

Thanks for opening your first pull request! We appreciate your
contribution. Please ensure you have reviewed and understood the
contributing guidelines.

If AI is used for any portion of this PR, you must vet the content
for technical accuracy.

Finally, be sure the PR description includes the PR
checklist,
and complete the items you are able to.

[cwhanse]

@JFrederico2022 pvlib should get only the functions, not the notebook. It has been a while since we discussed that: #2754 (comment) "In pvlib, a calcparams_villalva function would go into pvlib.pvsystem. Code for fitting would go into pvlib.ivtools.sdm in a new module villalva.py"

If you want, you can convert the notebook to a python script and add to the Example Gallery. Just start the script name with "plot_" and use docstrings where you want text to appear.