External cloning for CAC/PIV smartcards or PKI certs.

Problem to solve

Issue #726 (closed) solves the integration of CAC/PIV/PKI with GitLab, but cloning repositories from a command line or external IDEs may require more investigation and development effort.

Proposal

Support PIV/CAC use for git activity in a shell over SSH or HTTPS.

In the future, we may want to support specific IDEs like Eclipse.