Retain passwords in Git URLs (#1717)
Fixes handling of GitHub PATs in HTTPS URLs, which were otherwise
dropped. We now supporting the following authentication schemes:
```
git+https://<user>:<token>/...
git+https://<token>/...
```
On Windows, the username is required. We can consider adding a
special-case for this in the future, but this just matches libgit2's
behavior.
I tested with fine-grained tokens, OAuth tokens, and "classic" tokens.
There's test coverage for fine-grained tokens in CI where we use a real
private repository and PAT. Yes, the PAT is committed to make this test
usable by anyone. It has read-only permissions to the single repository,
expires Feb 1 2025, and is in an isolated organization and GitHub
account.
Does not yet address SSH authentication.
Related:
- https://github.com/astral-sh/uv/issues/1514
- https://github.com/astral-sh/uv/issues/1452
