feat(pypi): support freethreaded in experimental_index_url

[aignas]

With this we:

• Fix the previous behaviour where abi3 wheels would be selected when
  freethreaded builds are selected. Whilst this may work in practise
  sometimes, I am not sure it has been supported by reading PEP703.
• Start selecting cp313t wheels when we scan what is available on PyPI.
• Ensure that the whl_library repository rule handles cp313t wheel
  extraction.
• Generate cp313t config_settings so that we can use them in
  pkg_aliases.
• Generate cp313t references in pkg_aliases macro.
• Add the 3.13 deps to dev_pip for testing.

Also tested by manually running:

$ bazel cquery --//python/config_settings:python_version=3.13 --//python/config_settings:py_freethreaded=yes 'kind("py_library rule", deps(@dev_pip//markupsafe))'
INFO: Analyzed target @@_main~pip~dev_pip//markupsafe:markupsafe (3 packages loaded, 4091 targets configured).
INFO: Found 1 target...
@@_main~pip~dev_pip_313_markupsafe_cp313_cp313t_manylinux_2_17_x86_64_c0ef13ea//:pkg (008c5a5)
$bazel build --//python/config_settings:python_version=3.13 --//python/config_settings:py_freethreaded=yes @dev_pip//markupsafe

Fixes #2386