Add license management reports and parser

What does this MR do?

This MR adds a parser for a new CI license_management report. Which will be used later in an API point to serve it to the frontend.

The MR adds a license_management_report method to pipelines and adds a report comparison method to MRs.

What are the relevant issue numbers?

#7788 (closed)

CE MR : https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22833

Followup issues :

• https://gitlab.com/gitlab-org/gitlab-ee/issues/8196

Does this MR meet the acceptance criteria?

• [ ] Changelog entry added, if necessary
• [ ] Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• [ ] Conforms to the database guides
• EE specific content should be in the top level /ee folder
• [ ] For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?