uv-python-provider for managing Python installations

[d-m]

The uv tool can now support managing Python installations and would be a good candidate for a provider similar to pyenv-pants-provider.

Documentation for uv and how it can be used to install Python is here.

[sureshjoshi]

There is a WIP for the underlying functionality here (#19462)

Essentially using PBS directly. I think the PR just needs some TLC, and we're off to the races.

[huonw]

I reckon there's value in a uv provider, as it shifts the burden of security/recency out of Pants. In particular, Pants won't need to have a record of the sizes and hashes of each artifact, it's up to uv to manage that and Pants just needs to know how to install uv (already have support for it via downloading tools).

Thanks for the idea @d-m! Are you interested in working on this? Potentially we can get to good-enough by adapting the pyenv provider code.

[cburroughs]

pants.backend.python.providers.experimental.python_build_standalone has landed in main and will be in the next dev release. Feel free to take it for a spin!