[POC] gh-85454: Extract and inject distutils from setuptools whl

[tiran]

Extract the wheel from ensurepip's bundle and inject setuptools and
distutils into sys.path.

• Issue: Deprecate and remove distutils #85454

[tiran]

This looks kinda horrible but it works surprisingly well.

[encukou]

In the long term, pip will probably stop containing setuptools.
Maybe we should do this with sysconfig, at least for some platforms. It's something we could then also use in the tutorial: of course the tutorial should recommend third-party tools, from Cython to setuptools, but that should be links to their docs. IMO, it would be helpful to doc & test using sysconfig to get a bare-bones gcc/clang command line for a simple extension.

[pradyunsg]

FWIW, this isn’t a long-term concern: (puts on pip maintainer hat) we want to do it, for 3.12.

#95299

[vstinner]

Is this PR still relevant? It's now outdated. I closed #92584

[pradyunsg]

This is no longer relevant.