Add "security" top-level item to group sidebar
What does this MR do?
It moves the link to the "Security Dashboard" from sitting underneath "Project" to a new top-level tab.
Note.: This change will only be visible in EE - here is the related MR.
There is also a separate MR that includes related updates to the documentation: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31046
Edited by David Pisek