Code Review Analytics MVC - API Mock

Summary

Provide a page and Code Review Analytics API mock for FE to proceed with FE part of MVC

Details

• Page URL should be :group/:project/analytics/code_review
• API URL should be /api/v4/analytics/code_review
• Page and API mock should be accessible to Bronze+ plans and Starter+ licenses
• Page and API mock should be accessible to Reporter+ roles.
• Both Page and API should be behind code_review_analytics feature flag.

Response mock:

[
 {
   title: 'ABC',
   iid: 12345,
   web_url: 'https://gitlab.com/gitlab-org/gitlab/merge_requests/38062',
   created_at: TIMESTAMP,
   milestone: { id: 123, iid: 1234, title: '11.1', web_url: 'https://gitlab.com/gitlab-org/gitlab/merge_requests?milestone_title=12.7', due_date: TIMESTAMP},
   review_time: 64,
   author: { id: 123, username: 'foo', name: 'bar', web_url: 'https://gitlab.com/username', avatar_url: URL },
   approved_by: [SAME_STRUCTURE_AS_AUTHOR, ...],
   notes_count: 21,
   diff_stats: { additions: 504, deletions: 10, total: 514, commits_count: 7 }
 },
 {...}
]