text: Title: Implement GitLab 'List projects a user has contributed to'
  Body: ## Description of the problem, including code/CLI snippet
  This endpoint seems to be not implemented yet - at least, it is not documented:
  https://docs.gitlab.com/ee/api/projects.html#list-projects-a-user-has-contributed-to
  
  ## Expected Behavior
  I would love to see this endpoint implemented, as it makes filtering for contributed projects much easier.
  
  ## Specifications
  
    - python-gitlab version: v5.6.0
    - Gitlab server version (or gitlab.com): v17.9
  