Initialize a Git repository in `uv init` (#5476)
## Summary
Similiar to `cargo init --vcs <VCS>`, this PR adds the `--vcs <VCS>`
flag for `uv init`, allowing to create a version control system during
initialization. By default, `uv init` will create a Git repository if
the `--vcs` flag is not provided. Use `--vcs none` to disable this
feature.
Currently, only Git is supported. While Cargo also supports hg, pijul,
and fossil, this initial PR only includes Git. We can add more later if
there are any user requests.
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Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
