The normalized name abstractions were not consistently, this PR uses
them where they were previously missing:
* `WheelFilename::distribution`
* `Requirement::name`
* `Requirement::extras`
* `Metadata21::name`
* `Metadata21::provides_dist`
With `puffin-package` depending on `pep508_rs` this would be cyclical
crate dependency, so `puffin-normalize` gets split out from
`puffin-package`.
`DistInfoName` has the same task and semantics as `PackageName`, so it's
merged into the latter.
`PackageName` and `ExtraName` documentation is moved onto the type and
their constructors are called `new` instead of `normalize`. We now use
these constructors rarely enough the implicit allocation by
`to_string()` shouldn't matter anymore, while more actual cloning
becomes visible.
This needs far better error handling and user-facing feedback, but it
does the basic operation (and includes discovery of the `pyproject.toml`
file, etc.).
Charlie Marsh
konsti