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>

fedora.conf

@@ -106,12 +106,14 @@ lorax_options = [
   ('^.*$', {
      'x86_64': {
          'nomacboot': False,
-         'squashfs_only': True
+         'squashfs_only': True,
+         'configuration_file': 'lorax.conf'
      },
      '*': {
          'noupgrade': True,
          'rootfs_size': 3,
-         'squashfs_only': True
+         'squashfs_only': True,
+         'configuration_file': 'lorax.conf'
      }
   })
 ]

lorax.conf

@@ -0,0 +1,3 @@
+[compression]
+bcj = no
+args = -b 1M -Xdict-size 1M -no-recovery