python_site_packages_path can be specified in the build section

[jjhelmus]

Description

This is a implementation of CEP 17 in conda/ceps#90

The location of the site-packages directory can be specified in python_site_packages_path in the build section of a recipe. To avoid unnecessarily increasing the size of repodata this metadata should only be specified when the package name is python and when the path is not the default for CPython. These suggestions are not checked or enforced by conda-build.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[jjhelmus]

I created a few sample packages that specify this metadata field for testing with downstream tools. They are available on anaconda.org in the jjhelmus/label/sp_path channel.

There are three noarch packages with the following paths specified

• python 3.99.99 : lib/python3.99t/site-packages - A "free-threading" like path
• python 3.99.90 : sample_path/from_the_file/index_json - Something that stands out
• python 3.99.50 : ../../../../../invalid_path : Should be rejected by tooling as being invalid

[codspeed-hq]

CodSpeed Performance Report

Merging #5502 will not alter performance

_{Comparing jjhelmus:python_sp_path (dddf3f8) with main (d8a4148)}

Summary

✅ 5 untouched benchmarks

[jjhelmus]

@conda/builds-tools This PR is ready for a review.

[wolfv]

FYI we have a implementation in rattler build as well (will be released today):

prefix-dev/rattler-build#1161