rather than matching path of an existing remote to find the uuid.
The main benefit of this is that locations not using ssh:// will work
now, including both paths and host:/path
The other benefit is that it's a simpler interface, no need to have an
existing remote with the same url and some other name. Although that
will still work of course.
This does rely on tryGitConfigRead working when given a Git.Repo that is
not a remote. Luckily, it works fine that way.
Also, tryGitConfigRead will auto-init a local repo that has a git-annex
branch. I did not enable auto-init of ssh repos though.
The uuid discovery actually happens twice; initremote discovers it,
and uses it to store the special remote config, but does not set it in the
git remote it creates. So the next run of git-annex does uuid discovery
again, and caches it that time. This could be improved for a tiny
speedup, but I didn't want to complicate things for that in this
commit.
Sponsored-by: Dartmouth College's DANDI project
