web: clean up and reorganize site admin sidebar (!8051) · Merge requests · Administrator / sourcegraph

Created by: sqs

Moves site config and global settings into its own new group
Moves all user- and auth-related items into a "Users & auth" group
Moves up usage stats, surveys, and license into the top (overview group)
Removes singleton extensions group (item is moved to unlabeled existing "Other" group at bottom)
Renames "User surveys" to "Feedback survey" for clarity

web: clean up and reorganize site admin sidebar