Closes #ISSUE
## background
If a project is big, some times it will be splited into many small git
repos.
[google repo](https://gerrit.googlesource.com/git-repo/) is a tool to
manage a group of git repos.
But, any small git repo manged by this tool, have a difference with
normal git repo.
That is , the path `.git` in the root of the git repo, is not a normal
directory, but a soft link to real git bare dir.
### zed can not recognize the `git-repo` managed git repos
you can use the procedure to genreate this problem
```bash
# tested on linux
mkdir -p bad_git_repo_project
cd bad_git_repo_project
git init
echo "hello" > hi.txt
git add .
git commit -m "init commit"
echo "hello world" >> hi.txt
# modify the repo
mv .git ../.real_git_repo
ln -sf ../.real_git_repo .git
```
with vscode, after opening this project, git works well.
but for Zed, git not work(not git status, no git blame)
## how to fix
libgit2 can recognize git repo from the root of the project(dir that
have `.git`).
so, we can recognize the git project by opening from the project root
dir, but not the `.git` dir
This fix also works with normal git project.
### before fix
### after fix
Release Notes:
- Fix opening repos when .git is a soft link
e0cbbf8d06