Add optional "Code repo" button to projects

Created by: abelsromero

Is your feature request related to a problem? Please describe. Projects right now display a "Website" button in the summary in single views. I'd be nice to also link the code repo url when this is setup.

Describe the solution you'd like Same format and style as "Website" button is good for now. As nite-2-have, maby explore adding a git tree icon to make it git-provider agnostic.

Describe alternatives you've considered n/a

Additional context Related conversation: https://github.com/EclipseFdn/asciidoc-wg.eclipse.org/pull/64#issuecomment-827896870