Add optionl "Code repo" button to projects

[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: #64 (comment)

[abelsromero]

Created this issue for tracking

[ahus1]

While the original template is located in the Solstice theme https://github.com/EclipseFdn/hugo-solstice-theme/blob/master/layouts/projects/summary.html, it has already been copied in into https://github.com/EclipseFdn/asciidoc-wg.eclipse.org/blob/main/layouts/projects/summary.html

While all texts are stored in https://github.com/EclipseFdn/hugo-solstice-theme/blob/master/i18n/en.toml#L208, I'm happy to accept the text in the template "as is" hard coded - there is no plan to translate the site in the foreseeable future.