ipatests: Mark firewalld commands as no-op on non-firewalld distros
    
    The FreeIPA integration tests strictly require Firewalld.
    But not all the distros have such or any other high-level tool
    for managing a firewall. Thus, to run integration tests on such systems
    NoOpFirewall class has been added, which provides no-op firewalld
    commands.
    
    Fixes: https://pagure.io/freeipa/issue/8261
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: François Cami <fcami@redhat.com>
    Reviewed-By: Francois Cami <fcami@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>