make-people-page: Loop over directories, not users
    
    With IPA, enumerating users isn't easy and potentially expensive. Loop
    over home directories instead. In the course, use pathlib.Path instead
    of legacy interfaces for paths and pwd.getpwnam() to get information
    about users instead of spawning external pipes.
    
    Signed-off-by: Nils Philippsen <nils@redhat.com>