gh-142466: Pixi package definitions for downstream use

[lucascolley]

implementation for gh-142466, supporting numpy/numpy#30381 and scipy/scipy#24066.

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[lucascolley]

ping @FFY00 @hugovk @lysnikolaou

[StanFromIreland]

You need to update the branch to fix the CI.

[FFY00]

Thanks so much for working on this @lucascolley! This is PR looks great, and sets up to add other sanitizer variants.

The pixi limitation that requires us to have separate recipes for each variant (prefix-dev/pixi#4599) is unfortunate, but I think doable from a maintenance POV, given that we have a few people interested in this. We'll see how it translates in practice, and hope the feature request gets implemented in the meantime.

I opened prefix-dev/rattler-build#2047 regarding the version string that currently needs to be updated manually, but could be dirtermined from git, with additional information. But let's wait for the pixi jinja functions to get stabilized before adding them to our recipes.

I'll leave this PR open a couple days to give a bit more time for folks to give feedback, but otherwise, this looks good to go 😊