This patch makes a few changes to bring the protections panel closer in line with the Proton spec: 1) Add a few pixels of width to the tracking protection toggle switch. 2) Add underlining to the "site not working" link. 3) Replace the borders between sections of the panel with toolbarseparator elements, so that they become narrower than the panel width (and also match the panel header's separator). Differential Revision: https://phabricator.services.mozilla.com/D111717