Add IoT to 'wanted' images, exempt from checkwiki
    
    This is necessary to enable IoT testing. Adding IoT to the wiki
    is not done yet and is not going to be straightforward (we might
    need to handle it like we did Modular composes, when they were a
    thing) so we exempt it from checkwiki at least for now.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>