Check FAS for packager status, not pkgdb.
    
    Before this, we were consulting pkgdb to see if the given user was the
    maintainer of any packages.
    
    That mostly works... but technically, we want to consult FAS to see if
    the user is in the packager group.
    
    We found this when @mprahl was unable to submit builds to rida.  I added
    him to the packager group, but nothing changed!  (As written, he had to
    actually own a package).
    
    This change fixes all that so that we query FAS instead of pkgdb.
    
    Tests are added.