Specify the configuration_file in lorax_options
    
    Usage of this option should reduce both the BOOT.iso and the DVD medium size.
    This is because the LiveOS/squashfs.img will be compressed better by using
    a bigger dictionary size. 1MiB is the maximum allowed for SquashFS currently.
    
    This modification relates to the following change proposal:
    https://fedoraproject.org/wiki/Category:Changes/OptimizeSquashFS
    
    The result of it should be similar as in the following example DVD:
    https://khomutsky.com/fedora-dvd/Fedora-Workstation-x86_64-31-1.9.bkhomuts-squashfs-ext4-xz-1M.iso
    
    I have tested the above mentioned DVD myself to confirm that the installation
    succeeds. You can see other test results in the change proposal.
    
    Note, that this is only one part of the change proposal.
    A second part is documented at this URI: https://pagure.io/pungi-fedora/pull-request/871
    
    The new option requires Pungi 4.2.4 that will be released soon.
    
    Jira: RHELCMP-693
    Signed-off-by: Bohdan Khomutskyi <bkhomuts@redhat.com>