bug#38320: Cuirass: Allow to use authenticated Git repositories as inputs

[Mathieu Othacehe <m.othacehe@gmail.com>]

Hey!

> Apart from this detail, it looks great to me!
>
> You have push access, right?
>
> Speaking of which, we really need to push a release at some point.
> Erik, would you be available to do that, or would you like to delegate?

Great, thanks for reviewing :). I couldn't get it to work with a generated
client rsa key for an unknown reason, but pushed anyway.

Now regarding (guix git) integration, I have a question. It would be nice
to have "guix pull" and Cuirass support ssh authenticated
directories.

So "latest-repository-commit" could be call with ssh authentication
parameters. However, the guix-daemon won't be able to communicate with the
user ssh-agent, and storing an unencrypted private ssh key in the store
doesn't feel great to me.

Do you see any workaround?

Thanks,

Mathieu