Sync with distutils

[jaraco]

• Use minimum requirement for jaraco.functools
• use a real boolean (False) default for display_option_names generated attributes
• Fix issue with absolute path with Python 3.13 on Windows
• Accept an Iterable at runtime for Extension
• Add more tests to cover different iterables
• Delegate to os.fspath for type checking
• Fix typo
• Return real boolean from copy_file
• Fix test_mkpath_exception_uncached
• Set Py_GIL_DISABLED=1 for free threading on Windows
• Link to setuptools issue
• Trim the comment a bit.
• 👹 Feed the hobgoblins (delint).
• Use alternate spelling for flavor attribute.
• Only apply workaround on required Pythons.
• Let pathlib resolve the flavor.
• 👹 Feed the hobgoblins (delint).
• Run Ruff 0.8.0
• Add review suggestions around code comments
• Use TypeError instead of AssertionError
• UP031 manual fixes for Ruff 0.8.0
• Make reinitialize_command's return type Generic when "command" argument is a Command
• Coerce Distribution.script_args to list
• Remove py38 compat modules
• Remove UP036 exclusion.
• Prefer the standard format for imports, even though it's unnecessarily repetitive.
• type Distribution.get_command_obj to not return None with create=True
• ClassVar classvar mutables and tuple from typeshed
• 👹 Feed the hobgoblins (delint).
• Collapse startswith operations
• Use CFLAGS if set as-is, match CXXFLAGS behavior
• 👹 Feed the hobgoblins (delint).
• Don't duplicate CFLAGS
• 👹 Feed the hobgoblins (delint).
• Extract a classmethod _make_out_path_exts suitable for isolated testing.
• Re-write _make_relative to rely on pathlib for cross-platform and cross-python compatibility.
• Move suppress_path_mangle to test_ccompiler to limit the scope.
• Add tests and fix failure identified in the tests.
• Refactor for simplicity.

Summary of changes

Closes #4669

Pull Request Checklist

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