WIP: GitLab Selenium Proxy for screenshots and CI view

What does this MR do?

• GitLab Selenium Proxy for screenshots
• Add Selenium CI view at the job-level

Previous CE MR, https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17549

Are there points in the code the reviewer needs to double check?

How do I get this running locally?

1. Check out this MR
2. Run a pipeline locally that uses the GitLab Selenium proxy and saves the artifacts, mkdir -p selenium/ && curl -s http://localhost:4545/logs.tar.gz | tar -xvzf - -C selenium/
   • gitlab-ee in this branch uses it
   • https://gitlab.com/MadLittleMods/playing-with-selenium-on-gitlab-ci is probably easier to use
3. Click on the job that ran Selenium and switch to the Selenium tab at the top

Fixing flakey time-sensitve tests

• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19786
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19793
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19799
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19800
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19880
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19979

Refactor based on new artifact setup

The artifact system was refactored in https://gitlab.com/gitlab-org/gitlab-ce/issues/46809 but we still need the internal API to expose the data, https://gitlab.com/gitlab-org/gitlab-ce/issues/51647

• TODO: Update this MR with new format

Dev notes

• SELENIUM_REMOTE_URL=http://localhost:4545/wd/hub bundle exec spring rspec spec/features/issues/notes_on_issues_spec.rb (spec/features/issues/todo_spec.rb is also short and sweet)
• WIP: CI view on the pipeline-level, https://gitlab.com/gitlab-org/gitlab-ee/commit/605f0259711daf340300bad23431a519514950f8

Sidekiq NewNoteWorker/new_note queue affected by Selenium proxy (internal_references_spec.rb failure)

Slack discussion: https://gitlab.slack.com/archives/C02PF508L/p1528963806000272

Fix is here https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19979

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• EE specific content should be in the top level /ee folder
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/6278