GitHub Importer - Map GitHub Teams to GitLab during import

Problem to Solve

GitHub Teams are currently not migrated during import from GitHub into GitLab.

Proposed Solution

Consider importing Teams as Member-only subgroups. The concern with this solution is that GitHub Teams have a many-to-many relationship with repositories, while in GitLab, there is a 1-to-1 relationship between a project/subgroup and a repository.

A potential solution would be that we perform a "partial" import, where Teams are imported as subgroups, but those subgroups are "independent" from the projects that contain the repositories.