git integration: hide when not listing files in a Git repository

^{Originally posted by **Jackenmen** May 26, 2023}
Right now, enabling git column causes it to show in all directory listings, regardless of whether we're listing files inside a Git repository or not. In comparison, [`exa`](https://github.com/ogham/exa) only shows the Git column when running it inside a directory that is part of a Git repository (i.e. inside `~/git-repo` and `~/git-repo/subdir` but not inside `~`). I think that exa is better in this regard - it minimizes the clutter that isn't relevant when not run in a repository.

One potential edge case that you may want to handle is `tree` display mode where only part of a tree might be part of a Git repository. However, neither exa nor lsd currently shows the proper status on subdirectories that are git repositories so it would be fine to simply not show the git information at all.