These are not required because MySQL is not
supported anymore

Removed Registry from sidebar
Created new Packages top level item
Added Container Registry into packages
Updated tests to support new layout

Refactor code to allow multiple issue boards management for projects
in CE

Adds rspec view tests that expect the nav sidebar
to have a class that will cause the nav sidebar
to be rendered collapsed with or without js.

Tests the nav sidebar on the admin, group,
instance statistics, user profile and project
sidebars.

Compile highlight CSS separately
Move highlight-specific mixins out of mixins.scss
Rename solarized themes to match theme name as this was a smaller
change than changing all instances to snake_case

When the external wiki is enabled, the internal wiki link is replaced
by the external wiki url. But the internal wiki is still accessible.
In this change the external wiki will have its own tab in the sidebar
and only if the services are disabled the tab (and access rights)
will not be displayed.

We introduced releases_page feature flag.
Given this feature is deemed stable, we should remove
this flag before 19th.

Renders empty index page
Adds Releases entry to the navigation bar behind a feature flag
Renders 404 when feature flag for releases is not enabled