Installing packages with ssh auth #115

Feature request and a question:

There doesn't appear to be any detection of git ssh URI. When I pull from my private repositories I use a hardware GPG key as my git ssh authorization, since there is no easy way to exfiltrate the key. Can you add support for passing the raw ssh git URI and let git do the rest?

git@github.com:bpkg/bpkg.git
vs
https://github.com/bpkg/bpkg.git

Is there a way to install from a git clone on the local disk? I could just git clone everything to /tmp or /usr/local/src/ and use it like the ports system.