Move EE-specific files to a standalone directory

Closes #2902

See merge request !2483

https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2483#note_36713945

EE port of diff-changed-files-dropdown

See merge request !2586

Fixed a bad conflict resolution that caused duplicated links in project sidebar

See merge request !2593

Applying CE Patch for global deferred JS loading

See merge request !2569

Exclude sidekiq queues from execution in sidekiq-cluster

Closes #2893

See merge request !2571

* ee/master:
  Removed EE specific inline JS
  Don't include EmailHelpers manually, pick with rspec
  Mention EES in protected branches feature
  Port of fix-oauth-checkboxes to EE

Removed EE specific inline JS

See merge request !2592

EE: Don't include EmailHelpers manually, pick with rspec

See merge request !2591

Mention EES in protected branches feature

See merge request !2590

Port of fix-oauth-checkboxes to EE

See merge request !2588

* ee/master: (262 commits)
  Make dropdown style on project page consistent
  Remove :empty_project factory from spec/requests/api/merge_requests_spec.rb
  Fix merge conflicts
  Try to fix some EE protected branches specs
  Remove EE-specific usages of `:empty_project`
  Change all `:empty_project` to `:project`
  Remove `:empty_project` factory, implement `:repository` trait
  Remove documentation about `:empty_project` since we're removing it
  Use `:empty_project` where possible in features/steps
  Add filtered search to group issue dashboard (EE)
  Update milestone docs EE
  Port of 34027-add-icons-to-sidebar to EE
  Fix docs for using object storage for storing artifacts
  EE port of sidebar-fly-out-sub-nav
  Fix artifacts controller spec for object stores
  Resolve conflicts
  CI fixes for gitaly-ruby
  Fix LogCursor error message handler
  Add structured log messages to Geo LogCursor
  EE-specific changes for `:empty_project` and `:repository`
  ...

Fix docs for using object storage for storing artifacts

See merge request !2580

`:mailer` is needed to pick it easily, while
`type: :mailer` is needed for picking it automatically for
tests located in spec/mailers/*_spec.rb

It's a bit complicated in spec/services/notification_service_spec.rb
but we'll leave it alone for now.

Make dropdown style on project page consistent

See merge request !2577

CE upstream - Friday

Closes gitaly#408, gitaly#411, and #1827

See merge request !2554

EE port of sidebar-fly-out-sub-nav

See merge request !2576

Add structured log messages to Geo LogCursor

See merge request !2574