ipalib: move File command arguments to ipaclient
    
    File arguments are relevant only on the client, on the server they are the
    same as Str. Specify the arguments as Str in ipalib.plugins and override
    them with File in ipaclient.plugins.
    
    https://fedorahosted.org/freeipa/ticket/4739
    
    Reviewed-By: David Kupka <dkupka@redhat.com>