Let people file bugs for specific KCMs

When the active page has the BugReportUrl field set in its JSON
metadata, the "Report a Bug" menu item in the sidebar's hamburger menu
will now transform into a "Report a Bug in the Current Page" menu item that
will take you straight to the appropriate bug report entry page for the
current KCM.

BUG: 204364
FIXED-IN 5.27