Test UV behavior with git#egg= URLs

[arrdem]

A somewhat common case for internal repos is to use requirements files which reference internal forks of 3rdparty requirements via egg URLs. Test how uv add handles these and what the resulting lockfile looks like, make sure we have a story for these mostly just working.

Slightly concerned about translating git clone URLs to HTTP archive calls; may need to add support for actual git_repo usage.

[arrdem]

Turns out that the way UV encodes this is

[[package]]
name = "pure-python-adb"
version = "..."
source = { git = "....?rev=<commit-ish>" }

Which is a bit frustrating. We can parse the URL on the Bazel side and use a git_repository, but it creates some delta with the sdist flow which gets an archive and goes to a TreeArtifact of unpacked content since using a git_repository gives us not a TreeArtifact of sources but a directory full of fixed files which we may need to pass into the sbuild machinery differently.

For github at least a workaround is to move users from installs at commits to installs of archives of commits. We can't automate that in the extension because we don't know the shasum of the archive.