This PR adds a test that uses the Blivet interface to create an LVM
layout with ext4 filesystem as well as a postinstall test that checks
that the LVM layout has been created correctly.
When Fedora went to BTRFS as a default, we lost the LVM based image to
run LVM resize tests with.
This PR introduces the `install_lvm.pm` installation test that creates
an LVM based qcow2 image to be used by follow-up tests.