Add flag write_site_properties = False in CifWriter for writing Structure.site_properties as _atom_site_{prop}

[Andrew-S-Rosen]

Summary

Closes #3548 by adding a write_site_properties: bool = False keyword argument to CifWriter. Existing behavior is unchanged, but if write_site_properties = True, then the Structure object's site properties will be written out to the CIF file as atom site entries.

In principle, it would be nice to add a parser of custom site properties in CifParser, but I'll leave that to a separate PR.

Checklist

• Google format doc strings added. Check with ruff.
• Type annotations included. Check with mypy.
• Tests added for new features/fixes.
• If applicable, new classes/functions/modules have duecredit @due.dcite decorators to reference relevant papers by DOI (example)

Tip: Install pre-commit hooks to auto-check types and linting before every commit:

pip install -U pre-commit
pre-commit install

[Andrew-S-Rosen]

@janosh: This is ready for review!

Edited because I solved the issue.

[janosh]

Thanks @Andrew-S-Rosen, nice addition! 👍