This commit switches the identity popup to use "Content Blocking" as a top-level section
instead of Tracking Protection, which is now demoted to a category of Content Blocking.
To keep this change halfway reviewable, I avoided renaming variables, classNames, ids, etc.
that use the term trackingProtection if they were otherwise unaffected by this patch. There
will be other patches that can do this in the future
Differential Revision: https://phabricator.services.mozilla.com/D2775
4f70cfcab3