Before this PR freethreaded toolchains were not possible to be used,
this adds the minimum plumbing to get the things working. Coverage
support is also added.

Whilst at it:
- Add plumbing to print checksums only for a particular python version.
- Bump the remaining toolchain versions that used to use the 20241008
release
- Pass around the loaded platform list so that we are only defining
toolchains for the platforms that we have loaded the hermetic toolchain
for.

Tested:
```
$ bazel run --//python/config_settings:python_version=3.13.0 --//python/config_settings:py_freethreaded="yes" //python/private:current_interpreter_executable
...
Python 3.13.0 experimental free-threading build (main, Oct 16 2024, 03:26:14) [Clang 18.1.8 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>
```

Closes bazel-contrib#2129.
Work towards bazel-contrib#2386.

…-contrib#2391)

This just cleans up the code and moves more logic from the
repository_rule
(i.e. generation of `BUILD.bazel` files) to loading time (macro
evaluation).
This makes the unit testing easier and I plan to also move the code that
is
generating config setting names from filenames to this new macro, but
wanted to
submit this PR to reduce the review chunks.

Summary:
- Add a new `pkg_aliases` macro.
- Move logic and tests for creating WORKSPACE aliases.
- Move logic and tests bzlmod aliases.
- Move logic and tests bzlmod aliases with groups.
- Add a test for extra alias creation.
- Use `whl_alias` in `pypi` extension integration tests.
- Improve the serialization of `whl_alias` for passing to the pypi hub
repo.

Related to bazel-contrib#260, bazel-contrib#2386, bazel-contrib#2337, bazel-contrib#2319 - hopefully cleaning the code up
will make
it easier to address those feature requests later.

---------

Co-authored-by: Richard Levasseur <richardlev@gmail.com>

…rib#2412)

Here we remove the dependence on the `zstd` archive downloaded from GH
for extracting `zstd` toolchains because bazel now supports `zstd`
extraction for a long time.

This mainly cleans up the code which is again used a lot more due to
bazel-contrib#2386.

Co-authored-by: Richard Levasseur <rlevasseur@google.com>

…azel-contrib#2406)

Before this PR we would shell out to `uname` on UNIX systems to get the
`arch`
of the toolchain - on Windows we would not need to do it because there
used to
be only a single Windows platform. With this change we can correctly
support
the resolution of the python interpreter on various platforms and I have
also
added an env variable to customize the selection, so that users can use
`musl`
or a `freethreaded` interpreter if they wish.

As part of this change, I have restricted visibility of the config
settings
used in the toolchain alias repo so that we are creating fewer targets.
This is
a very good time to do this before `1.0.0`.

Fixes bazel-contrib#2145
Work towards bazel-contrib#2276
Work towards bazel-contrib#2386
Work towards bazel-contrib#1211 to unblock bazel-contrib#2402
Work towards bazel-contrib#1361

---------

Co-authored-by: Richard Levasseur <richardlev@gmail.com>

…trib#2460)

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 bazel-contrib#2386

Support is implemented, just documenting this is left.

Fixes bazel-contrib#2386