In pylock.toml export, include dependencies (name and version)

[pimdh]

Summary

In the code for export a lock file to pylock.toml, I added the [[packages.dependencies]] field (https://packaging.python.org/en/latest/specifications/pylock-toml/#packages-dependencies). The goal of this change is to utilize uv to generate lockfiles for use with Pants and PEX (see pantsbuild/pants#22201).

Fixes #13032.

Details:

• Because this dependency field is not fully specified, I only include the package's name and version, which seems sufficient for integrating the resulting files with Pants and Pex.
• I didn't add the dependencies to from_resolution, because I don't need it, and because it wasn't immediately clear to me how the edges and nodes in the resolution graph would have to be filtered.
• I filter the dependencies based on those selected by ExportableRequirements::from_lock for inclusion in the lockfile.

Test Plan

I've updated the tests to include the dependencies.

[pimdh]

I see where the tests are now. Fixing them.

[pimdh]

I've added the dependencies to the tests, and fixed the linting.

[charliermarsh]

Thanks @pimdh. We technically might be required to add (e.g.) the VCS annotations and such here... I need to review the spec.

[jsirois]

FWIW, I think name and version is not enough to cover all uv.locks. My analysis here: #13032 (comment)