Gitlab support

[frob]

Is your feature request related to a problem? Please describe.

Not every organization uses Github many use Gitlab. Supporting Github and Gitlab would cover the 90% usecase.

Describe the solution you'd like

Templates for both Gitlab and Github

Describe alternatives you've considered

While it would be possible to build this out in Github and then add a Gitlab origin, none of the github actions would continue to work.

[lpm0073]

Yes @frob, point taken.
Question: does Gitlab has a public registry / marketplace for "actions" similar to the Github Actions Marketplace? If so, then the immediate next step would be to port these actions to Gitlab: https://github.com/openedx-actions