Add parent subgroup creation for ADO project with multiple repos

Overview

To have a complete support of option 1 we need to implement functionality to create subgroup for the ADO project that has multiple repos (see scenario below):

for project in projects
   if project.repos > 1
      store project as GitLab group

Implementation should be based on GitLab Group file based export which gives us solid foundation for transformation of various types of data available in export.

Tasks

• Update docs if needed (workflow, runbooks, README, migration metrics, etc.)

Acceptance Criteria

• Existing UTs pass locally
• 100% code coverage on new code

@gitlab-org/professional-services-automation/tools/migration