Adding distro install paths to the python files

[LecrisUT]

Background

The Fedora package of pybind11 is split into pybind11-devel and python3-pybind11 where the former contains the artifacts built from direct cmake installation under /usr and the latter contains the python files and metadata. There are some patches done to the python files to change the root path

pybind11/pybind11/commands.py

Line 5 in c630e22

DIR = os.path.abspath(os.path.dirname(__file__))

to point to /usr.

I believe there could be a better way to support this, after the scikit-build-core refactor.

Generated python files

One approach I am considering is to allow the python build to build without bundling the CMake files, and instead either find_package(pybind11) or manually provide a pybind11_ROOT which would do the same patch as described previously.

Getting rid of the -devel package

This is also an option, but I would want to check what is upstream's support plan. Is the build without python build backend supposed to be supported in the long run? Are there plans to allow non-header-only builds? Depending on these it could make sense to either improve the support or get rid of the -devel split.