This runs a slightly slower query to get the issue and MR counts in the
navigation, but caches by user type (can see all / none confidential issues) for
two minutes.

When we are filtering by a single project, and the current user has access to
see confidential issues on that project, we don't need to filter by
confidentiality at all - just as if the user were an admin.

The filter by confidentiality often picks a non-optimal query plan: for
instance, AND-ing the results of all issues in the project (a relatively small
set), and all issues in the states requested (a huge set), rather than just
starting small and winnowing further.

Rename other URL generators

admin_builds_path -> admin_jobs_path

Fix tests and more renaming

Fix more tests

Also change build_id to job_id in the controller

Rename Build to Job

Replace "Builds" by "Jobs" and fix broken specs

Replace "Builds" by "Jobs"

Fix broken spinach test

Fix broken test

Remove `˙` at the beginning of the file

Fix broken spinach test

Fix broken tests

Changes after review

Replace MR access checks with use of MergeRequestsFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

⚠ - Potentially untested
💣 - No test coverage
🚥 - Test coverage of some sort exists (a test failed when error raised)
🚦 - Test coverage of return value (a test failed when nil used)
✅ - Permissions check tested

- [x] 💣  app/finders/notes_finder.rb:17
- [x] ⚠  app/views/layouts/nav/_project.html.haml:80 [`.count`]
- [x] 💣  app/controllers/concerns/creates_commit.rb:84
- [x] 🚥  app/controllers/projects/commits_controller.rb:24
- [x] 🚥  app/controllers/projects/compare_controller.rb:56
- [x] 🚦  app/controllers/projects/discussions_controller.rb:29
- [x] ✅  app/controllers/projects/todos_controller.rb:27
- [x] 🚦  app/models/commit.rb:268
- [x] ✅ lib/gitlab/search_results.rb:71

- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#d1c10892daedb4d4dd3d4b12b6d071091eea83df_267_266 Memoize ` merged_merge_request(current_user)`
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#d1c10892daedb4d4dd3d4b12b6d071091eea83df_248_247 Expected side effect for `merged_merge_request!`, consider `skip_authorization: true`.
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#d1c10892daedb4d4dd3d4b12b6d071091eea83df_269_269 Scary use  of unchecked `merged_merge_request?`

See merge request !2033

Replace issue access checks with use of IssuableFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

## Which fixes are in this MR?

⚠ - Potentially untested  
💣 - No test coverage  
🚥 - Test coverage of some sort exists (a test failed when error raised)  
🚦 - Test coverage of return value (a test failed when nil used)  
✅ - Permissions check tested

### Issue lookup with access check

Using `visible_to_user` likely makes these security issues too. See [Code smells](#code-smells).

- [x] 🚦 app/finders/notes_finder.rb:15 [`visible_to_user`]
- [x] 🚥 app/views/layouts/nav/_project.html.haml:73 [`visible_to_user`] [`.count`]
- [x] ✅ app/services/merge_requests/build_service.rb:84 [`issue.try(:confidential?)`]
- [x] ✅ lib/api/issues.rb:112 [`visible_to_user`]
  - CHANGELOG: Prevented API returning issues set to 'Only team members' to everyone
- [x] ✅ lib/api/helpers.rb:126 [`can?(current_user, :read_issue, issue)`] Maybe here too?
- [x] ✅ lib/gitlab/search_results.rb:53 [`visible_to_user`]

### Previous discussions
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b2ff264eddf9819d7693c14ae213d941494fe2b3_128_126
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#7b6375270d22f880bdcb085e47b519b426a5c6c7_87_87

See merge request !2031

Updated specs

Closes #21218

Prior, in order to display the correct link to "Issues" in the project
navigation, we were performing a check against the project to see if it
used an external issue tracker, and if so, we used that URL. This was
inefficient.

Now, we simply _always_ link to `namespace_project_issues_path`, and
then in the controller we redirect to the external tracker if it's
present.

This also removes the need for the url_for_issue helper. Bonus! 🎉

And create new Project#requesters, Group#requesters scopes.
Signed-off-by: NRémy Coutable <remy@rymai.me>

Closes #18830

Signed-off-by: NRémy Coutable <remy@rymai.me>

Signed-off-by: NRémy Coutable <remy@rymai.me>

This reverts commit 13e37a3e.