WIP: Using the Gitlab selenium proxy for fingerprinting screenshots for test

What does this MR do?

See gitlab-selenium-server#5

Sends the description of each spec to Gitlab selenium server to be used in fingerprinting screenshots

To test run SELENIUM_REMOTE_URL=http://localhost:4545/wd/hub bundle exec spring rspec spec/features/issues/notes_on_issues_spec.rb

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

Based off of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17549

Why was this MR needed?

Screenshots (if relevant)

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
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

See gitlab-selenium-server#5