keep upload files locally, activate network in kickstarts
    
    Summary:
    I've come to dislike the approach where we source files that
    get included in the disk images remotely; it's unnecessarily
    complicated and needlessly exposes us to unexpected changes in
    the remote files. So simply keep the files in this git repo
    instead, none of them is very big. This also simplifies the
    code.
    
    Also, change all the kickstarts to specify --device=link and
    --activate on their network lines. These arguments *should*
    be included, according to the documentation (the first to
    specify which device the config is for, the second to specify
    that it should be activated in the installer environment), and
    I think the lack of the second is actually now a problem for
    the FreeIPA kickstart enrolment test (not sure exactly what
    changed to make this a problem where it wasn't before, but
    *something* has, and this fixes it).
    
    Test Plan:
    check that all tests still run properly. The
    FreeIPA enrolment kickstart test should now get somewhat
    further. Before this change, for F25 and Rawhide, it fails to
    enrol at all during install. Now it should enrol properly -
    that's what the kickstart changes fix, it was failing because
    it wasn't using the right network config - but it still fails
    when trying to log in as test1, due to RHBZ #1366403 .
    
    Reviewers: jskladan, garretraziel
    
    Reviewed By: garretraziel
    
    Subscribers: tflink
    
    Differential Revision: https://phab.qadevel.cloud.fedoraproject.org/D968