build: refactor build infrastructure

[nstarman]

This PR refactors the build infrastructure to

1. remove the setup.py in favor of pyproject.toml
2. dynamically generate the version from the pyproject (this is not a VCS dynamic versioning)
3. be compatible with uv but still all other tools, like conda,
4. use src folder layout.

[fehiepsi]

Hi @nstarman, thanks for the refactor. We would prefer to keep the current setup. I'm not sure why we need to be compatible with uv (shouldn't uv thing be compatible with the python ecosystem?) and why we need to use the src layout.

[nstarman]

uv is compatible with the python ecosystem. It just adds config to pyproject.toml for development and adds a lockfile, which is useful.
Is there a reason for keeping the outdated setup.py?
When I've been doing dev in my last PR my editable build is producing a numpyro.egg-info in the top-level env. The src layout is better for isolating dev environments. Because of git-mv current PRs can rebase without consequence.

[fehiepsi]

re setup.py: https://packaging.python.org/en/latest/discussions/setup-py-deprecated/#setup-py-deprecated

[nstarman]

re setup.py: https://packaging.python.org/en/latest/discussions/setup-py-deprecated/#setup-py-deprecated

Yes, it's not deprecated. I was careful to use "outdated" as new standards have superseded setup.py, offering standardization, better integrations with developer tooling, safety from arbitrary code execution, improved reproducibility in builds, support for PEP 517/518, and longevity (version 21.3 of pip has started moving away from supporting editable installs via setup.py)

[fehiepsi]

Thanks. Could you make a new PR just for setup.py changes?