add QA:Testcase_desktop_browser test
    
    Summary:
    pretty simple stuff here. The distinction between 'firefox' and
    'browser' is that the 'browser' needles I expect would also be
    correct for other default browsers, while the 'firefox' needles
    are specific to Firefox. We need '-kde' variants of some Firefox
    needles where interface text is included, because the font is
    Cantarell in GNOME but whatever the default 'sans' font is in
    KDE - I suppose we should really use -thatfontsname rather than
    -kde, but I can't think what it's called...
    
    I couldn't do the 'log in to FAS' bit of the test since we don't
    really have a sane way to provide a password while not exposing
    it to the public.
    
    Test Plan:
    Run the test, check it works - for both KDE and
    Workstation.
    
    Reviewers: jskladan, garretraziel
    
    Reviewed By: garretraziel
    
    Subscribers: tflink
    
    Differential Revision: https://phab.qadevel.cloud.fedoraproject.org/D938