refactor: move to GitLab

Description

Branches off from gabor/replace-ci. Replace github references with Gitlab.

Testing instructions

• Proofread the changes
• Check the pipelines for anything out of the ordinary:
  • Currently running: https://gitlab.com/opencraft/dev/console/-/pipelines
  • Successful staging deploy: https://gitlab.com/opencraft/dev/console/-/pipelines/619698799
• Check the documentation: https://ocim.opencraft.com/en/keith-move-ocim-to-gitlab/