Build: Simplified `setup.py`

[t20100]

Merge PR #3649 first!

This PR cleans-up/removes features from setup.py since:

running python setup.py directly as a script is considered deprecated. This also means that users should avoid running commands directly via python setup.py <command>.

https://setuptools.pypa.io/en/latest/deprecated/commands.html

We can look at packages such as invoke for this.

This PR:

• Removes setup.py commands:

  • Remove python setup.py test (https://github.com/silx-kit/silx/commit/84b3d7047ccb74f1a7bca1e62258a63209181695): There is run_test.py for it.
  • Remove python setup.py build_doc &cie and document how to call sphinx directly (https://github.com/silx-kit/silx/commit/ea1d920da1964075886c75c1b5e0419872a39f7b): Sphinx setuptools integration is deprecated.
  • Remove python setup.py clean override (https://github.com/silx-kit/silx/commit/c9db62e9f2ff09d1fbdd4fd6bdf512b83caeb9da): There is no equivalent for that, but it allows to get rid of the last distutils import.

• Prepares for not calling setup.py build directly:

  • Deprecate python setup.py build arguments (--no-openmp, --openmp, --force-cython) and document the env. var. that provides the same feature (https://github.com/silx-kit/silx/commit/e5ee93adcf04f369cf523df507db4bac3262cfda and https://github.com/silx-kit/silx/commit/d080eafc1a7b1b7b42fc471b7f88a561b6297a04). I renamed the env. var. with a SILX_ prefix while at it.
  • Rework and document SPECFILE_USE_GNU_SOURCE (https://github.com/silx-kit/silx/commit/ba22270b8ccb596ae9869ec54d969cf2b5897c1e).
  • Document SILX_FULL_INSTALL_REQUIRES and SILX_INSTALL_REQUIRES_STRIP env. var. (https://github.com/silx-kit/silx/commit/6ae33008c7bbe348757e7e7d819e09170eea8dd6)

• Misc:

  • Fixed documentation by de duplicating the doc of silx.io.commonh5.Group (https://github.com/silx-kit/silx/commit/75324d254156b2965e8913d62766951abc52c96a)
  • Simplify setup kwargs (https://github.com/silx-kit/silx/commit/c02fec2558ffd6352ed244a64cebdf2cd3d0f711)

With this PR, setup.py no longer rely on distutils. 2 setup.py commands remains (build_man and debian_src) which are related to Linux packaging.

closes #3574

[t20100]

Release CI passes with this PR: https://gitlab.esrf.fr/silx/bob/silx/-/pipelines/85576

[t20100]

Rebased to master, ready for review

[vallsv]

I dont like much env var for build. Is that a real problem to support such options?

What is the aim?

Else, i am fine with it anyway.

[t20100]

I dont like much env var for build. Is that a real problem to support such options?

Neither do I... but "running python setup.py directly as a script is considered deprecated.", and passing options through pip's --global-option is more complex than using env. var. and anyway not self documented.

What is the aim?

Be future-proof