Adds js unit tests

Adds tests

This reverts commit e00fb2bdc2090e9cabeb1eb35a2672a882cc96e9.

# Conflicts:
#	.rubocop.yml
#	.rubocop_todo.yml
#	lib/gitlab/ci/config/entry/global.rb
#	lib/gitlab/ci/config/entry/jobs.rb
#	spec/lib/gitlab/ci/config/entry/factory_spec.rb
#	spec/lib/gitlab/ci/config/entry/global_spec.rb
#	spec/lib/gitlab/ci/config/entry/job_spec.rb
#	spec/lib/gitlab/ci/status/build/factory_spec.rb
#	spec/lib/gitlab/incoming_email_spec.rb

This reverts commit cb10b725c8929b8b4460f89c9d96c773af39ba6b.

This reverts commit 96bef54154e669f9a3e92c3a4bc76c0be3a52e48.

stub pagination in tests

Fix broken test

Fix rubocop error

In an effort to tackle #18437 this removes 2 of the jQuery UI plugins. Highlight & autocomplete, both used once in our code. Highlight was just removed easily, autocomplete was replaced with GL dropdown

Creates individual html for dropdown
Adds simplified  CSS for the new dropdown
Removes old CSS
Improves dropdown item in Chrome, Firefox and Safari
Use SCSS variables for colors.
Fix scss linter errors
Adds animation when the stage is hovered.
Adds back tooltip on dropdown toggle
Fixes broken tests
additional css changes to get more into direction of mockups

Changes after review