Address circular imports complaints by Sphinx 7.2+

[abravalheri]

Summary of changes

The latest version of sphinx started failing in #4020 (comment) due to circular imports.

Examples of the error messages are:

ImportError: cannot import name 'Distribution' from partially initialized module 'setuptools.dist'

AttributeError: partially initialized module 'setuptools' has no attribute 'version' (most likely due to a circular import)

Failed to import class 'Command' from module 'setuptools'

In this PR, I am attempting to address this problem.

The approach I used was:

• Rewrite the imports in setuptools/__init__.py, setuptools/monkey.py and setuptools/dist.py to avoid circular imports.
  • I also took this chance to try to tide up a bit (e.g. sorting them, separating import ... and from ... import ... statements, etc)
• I had to change slightly the way we are importing setuptools.extern.packaging and setuptools/depends.py and setuptools/tests/test_setuptools.py because for some reason the tests where complaining that the Version class was differing from itself (maybe the module is loaded twice?)

Closes

Pull Request Checklist

• Changes have tests
• News fragment added in newsfragments/.
  (See documentation for details)

[abravalheri]

Since the problem with sphinx seems to be impacting other users, I will go ahead and merge this as soon as the CI is green (but I will not immediately publish a new release). Hopefully it is just some refactoring that does not impact negatively the project.