Create new method to headlessly bootstrap Gitlab

Problem to solve

When running gitlab-ce in Docker, it used to be possible to use the session endpoint with root username/password to create an API session and bootstrap Gitlab with projects.

See: https://github.com/andrewshawcare/docker-ecosystem-gitlab/blob/master/project-importer/entrypoint.sh

The aforementioned project used to be able to start Gitlab CE, a Gitlab agent, and an ephemeral container named, "project-importer." Once the API was available, the project-importer would create an API session, add various projects to GitLab, and trigger a build for the first project in the pipeline.

Since the session endpoint has been removed, there appears to be no way to bootstrap Gitlab headlessly.

Proposal

What does success look like, and how can we measure that?

Have a way to allow for bootstrapping Gitlab using the API or by some other means (e.g. Jenkins has their Groovy API, GoCD has their XML config files).