consume .whl.METADATA files when available

[graingert]

What's the problem this feature will solve?

Currently a number of projects are trying to work around the fact that in order to resolve dependencies in Python you have to download the entire wheel in order to read the metadata. I am aware of two current strategies for working around this, one is the attempt to use the PyPI JSON API (which isn't a good solution because it's non standard, the data model is wrong, and it's not going to be secured by TUF) and the other is attempting to use range requests to fetch only the METADATA file from the wheel before downloading the entire wheel (which isn't a good solution because TUF can currently only verify entire files, and it depends on the server supporting range requests, which not every mirror is going to support).

Describe the solution you'd like

consume .whl.METADATA files when available pypi/warehouse#8254

Alternative Solutions

N/A

Additional context

N/A