This changes GetRepoPaths() to pull information from `git rev-parse`
instead of effectively reimplementing git's logic for pathfinding. This
change fixes issues with bare repos, esp. versioned homedir use cases,
by aligning lazygit's path handling to what git itself does.
This change also enables lazygit to run from arbitrary subdirectories of
a repository, including correct handling of symlinks, including "deep"
symlinks into a repo, worktree, a repo's submodules, etc.
Integration tests are now resilient against unintended side effects from
the host's environment variables. Of necessity, $PATH and $TERM are the
only env vars allowed through now.
This was on oversight on my part: I assumed that the --work-tree arg was
always intended for use with linked worktrees which have a .git file
pointing back to the repo.
I'm honestly confused now: seems like there are three kinds of worktrees:
* the main worktree of a non-bare repo
* a linked worktree (with its own gitdir in the repo's worktrees/ dir)
* a random folder which you specify as a worktree with the --work-tree arg
I'm pretty sure the --work-tree arg is only intended to be used with this
third kind or workree
