Add ability to drive the API in QA specs

What does this MR do?

Adds the basic methods for calling the GitLab API in QA specs. Forms the basis for adding QA specs for Geo API

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• [-] Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • [-] Has been reviewed by UX
  • [-] Has been reviewed by Frontend
  • [-] Has been reviewed by Backend
  • [-] Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• [-] Internationalization required/considered

What are the relevant issue numbers?

Related to gitlab-qa#131 (closed) and gitlab-qa#149 (closed)