QA/TestCases/Ext3toExt4Migration

Description
Support the migration of an existing ext3 filesystem to ext4 during upgrade. (or, at least, to the extents feature) Files replaced during the upgrade should be created in the new extents format.

When the upgrade/migration is finished, the system should boot and mount the filesystem(s) as ext4, and any new files from the upgrade should be in the new extents format.

Note that this is a "hidden" boot option and requires a boot-time parameter, but testing will give confidence that it could be made more readily available in the future.

References:
 * 1) Resolved ext3->ext4 migration bug
 * 2) ext4 test day migration test

Steps To Reproduce

 * Boot the F10 installer
 * Do a default install to ext3
 * complete installation
 * reboot into post-install system and complete firstboot etc
 * Boot the F11 installer with the  boot option
 * Upgrade the system and answer yes to the migration question
 * complete upgrade
 * reboot into post-install system
 * run
 * files which have been upgraded
 * reboot to rescue mode and run  on root filesystem

Expected Results
in post-install system, verify:
 * installation completes successfully
 * post-installation system boots
 * upgrade completes successfully
 * post-upgrade system boots
 * post-upgrade system is functional
 * post-upgrade system has old ext3 root mounted as ext4
 * post-upgrade system shows "extents" in tune2fs output for root ext4 fs
 * post-upgrade new files show -e- in lsattr output
 * post-upgrade root filesystem fscks cleanly