Promote EE features

Closes #2887, #2888, #2918, #2966, #2987, #2988, and #2967

See merge request !2540

Move EE specific files (_ee) to the EE directory

See merge request !2673

Port of remove-sidebar-title to EE

See merge request !2672

Adds CE to EE compatibility with 2756

See merge request !2788

EE API delete respect headers

See merge request !2782

Add my-reaction filter (EE)

Closes #1938

See merge request !2778

Merge branch '3233-project-mirror-not-actually-active-when-new-project-is-created-fix' into 'master'

Fixes activation of project mirror when project is created.

Closes #3233

See merge request !2756

* ee/master: (841 commits)
  Simplify License#load_license method
  Add CHANGELOG
  Fix License.feature_available? when license table does not exist
  Move ConvDev index to Overview from Monitoring.
  Remove unnecessary divider
  Update CHANGELOG.md for 9.5.2
  Update CHANGELOG-EE.md for 9.5.2-ee
  Fix doc
  Fix doc
  Add tests
  Update .gitlab-ci.yml
  Update build.rb
  Add changelog
  ini
  SSH pull repository mirroring was introduced in 9.5, not 9.15
  Fire system hooks when a user is created via LDAP or OAuth
  Remove skipped examples in filtered issues weight feature spec
  Limit Geo LogCursor spec to run only on PostgreSQL
  Remove duplicated items from admin sidebar
  Common Docker Documentation Location in `gitlab-ce`
  ...

Check if `licenses` table exists before loading the current license.

Closes #3280

See merge request !2783

Move ConvDev index to Overview from Monitoring (EE Compatible Version)

See merge request !2732

Support `codequality` job name for Code Quality feature

Closes #2783

See merge request !2704

Remove unnecessary divider

See merge request !2771

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