fix(pypi): select the lowest available libc version by default (#3255)

The #3058 PR has subtly changed the default behaviour of
`experimental_index_url` code path and I think in order to make things
easier by default for our users we should go back to that behaviour.

And in addition to this we are starting to make use of the Minimal
Version Selection algorithm for the platforms. This in general allows
users to configure the upper platform version for a particular wheel.
This meant that we had to change the semantics of the API a little:
1. Use MVS for each platform platform tag.
2. Make it such that earlier entries are overridden by later ones, i.e.
   `["musllinux_*_x86_64", "musllinux_1_2_x86_64"]` is effectively the
   same as just `["musllinux_1_2_x86_64"]`.

A remaining thing that will be left as a followup for #2747 will be to
figure out how to allow users to ignore certain platform tags.

Fixes #3250

---------

Co-authored-by: Richard Levasseur <richardlev@gmail.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>