move build configuration to pyproject.toml, remove setup.py

Created by: PhilipVinc

In recent years there's been a push to deprecate declaring the build option of python packages with the overly complicated setup.py in favour of static build declaration in a pyproject.toml file together with one of many build tools (hatch, poetry...).

With the release of Python 3.11 next week, setup.py will be officially deprecated by setuptools as well (our current build system). The deprecation will probably last many years, but as we already require users to have a recent pip version (jax cannot be installed with pip older than 1 year or so), there's nothing bad with migrating to the new standard.

This PR is a draft at migrating our build configuration to pyproject. I'm going to keep it around so that I don't forget.