This makes it so the presence of `.jj` will cause ripgrep to treat it
as a VCS directory, just as if `.git` were present. This is useful for
ripgrep's default behavior when working with jj repositories that don't
have a `.git` but do have `.gitignore`. Namely, ripgrep requires the
presence of a VCS repository in order to respect `.gitignore`.
We don't handle clone-specific exclude rules for jj repositories without
`.git` though. It seems it isn't 100% set yet where we can find
those[1].
Closes#2842
[1]: https://github.com/BurntSushi/ripgrep/pull/2842#discussion_r2020076722
94ea38da30