feat(dmdquash-live): add support for using erofs

This adds support for rootfs compressed with erofs. Either as a plain
erofs image or a LiveOS/rootfs.img ext4 filesystem compressed with
erofs.

This patch does not make any attempt to change the squashfs directory
naming (or variable names) in order to make these changes as small as
possible and easy to review. It also does not make any attempt to
support the multitude of available options other than what is needed by
anaconda-dracut calling this script to setup the boot.iso root
filesystem.

(which isn't to say it doesn't work, it just hasn't been tested and is
outside the scope of this change).

(cherry picked commit ca5ae5d)

Resolves: RHEL-43460

modules.d/90dmsquash-live/dmsquash-live-root.sh

@@ -97,7 +97,6 @@ det_img_fs() {
     blkid -s TYPE -u noraid -o value "$1"
 }
 
-load_fstype squashfs
 CMDLINE=$(getcmdline)
 for arg in $CMDLINE; do
     case $arg in
@@ -112,14 +111,15 @@ if [ -f "$livedev" ]; then
     # check filesystem type and handle accordingly
     fstype=$(det_img_fs "$livedev")
     case $fstype in
-        squashfs) SQUASHED=$livedev ;;
-        auto) die "cannot mount live image (unknown filesystem type)" ;;
+        squashfs | erofs) SQUASHED=$livedev ;;
+        auto) die "cannot mount live image (unknown filesystem type $fstype)" ;;
         *) FSIMG=$livedev ;;
     esac
     load_fstype "$fstype"
 else
     livedev_fstype=$(det_fs "$livedev")
-    if [ "$livedev_fstype" = "squashfs" ]; then
+    load_fstype "$livedev_fstype"
+    if [ "$livedev_fstype" = "squashfs" ] || [ "$livedev_fstype" = "erofs" ]; then
         # no mount needed - we've already got the LiveOS image in $livedev
         SQUASHED=$livedev
     elif [ "$livedev_fstype" != "ntfs" ]; then
@@ -336,7 +336,7 @@ if [ -e "$SQUASHED" ]; then
     SQUASHED_LOOPDEV=$(losetup -f)
     losetup -r "$SQUASHED_LOOPDEV" $SQUASHED
     mkdir -m 0755 -p /run/initramfs/squashfs
-    mount -n -t squashfs -o ro "$SQUASHED_LOOPDEV" /run/initramfs/squashfs
+    mount -n -o ro "$SQUASHED_LOOPDEV" /run/initramfs/squashfs
 
     if [ -d /run/initramfs/squashfs/LiveOS ]; then
         if [ -f /run/initramfs/squashfs/LiveOS/rootfs.img ]; then