Add GitLab SSH Keys

[adam-moss]

Is your feature request related to a problem? Please describe.
Similar to GitHub, it would be great if we could ascertain GitLab ssh keys.

Describe the solution you'd like

• Identify keys that are used in GitLab
• Identify keys that are used in both GitHub and GitLab

Describe alternatives you've considered
Custom python scripts

Additional context

[dustin-decker]

This is already supported in TruffleHog v3, by the way. We haven't updated the driftwood CLI in a while but intend to add it here too.

https://github.com/trufflesecurity/trufflehog