Add project operations index to global nav

• Follow up from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24565 // https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9253
• Adds user/project/operations/index.html to the global nav
• For gitlab-com&21 (closed) and &548

Note: the pipeline will pass once CE/EE gets merged.

TODOS:

• Merge https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9253
• Merge https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24565
• Run pipeline here again
• Merge this MR