Normalize wheel distribution names to match the PyPA spec

[artob]

This fixes building publishable sdists and wheels for packages where the name contains a dot (aka period, aka full stop). For example, asimov.py gets normalized into "asimov_py":

$ ls -1 target/wheels/
asimov_py-26.0.0.dev1-cp314-cp314-macosx_11_0_arm64.whl
asimov_py-26.0.0.dev1.tar.gz

Note some relevant history regarding distribution name normalization:

1. The PEP 427 (2012) specification contained the regular expression [^\w\d.]+ which preserved dots.
2. Popular tools (pip, setuptools, etc.) didn't actually follow this: instead, they replaced dots with underscores.
3. The PyPA Binary Distribution Format specification was updated (in 2021) to match what tools actually did, explicitly requiring dots to be replaced with underscores.

[messense]

Thanks!

[Copilot]

Pull request overview

Updates distribution-name normalization to align with the current PyPA Binary Distribution Format spec so wheels/sdists are publishable when project names contain dots.

Changes:

• Normalize distribution names by collapsing runs of -_. into _ and lowercasing for wheel/sdist filenames and .dist-info naming.
• Update docstring to reflect the PyPA spec and how the normalized name is used.
• Remove the WASI-only build guard that rejected names containing dots (now normalized away).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/metadata.rs	Adjusts get_distribution_escaped() normalization behavior and updates its documentation accordingly.
src/build_context.rs	Removes WASI dot-in-name rejection that is no longer relevant with the new normalization.