Remove ext4+squashfs image type support
This mode has very little, if any, use cases for archiso. The only advantage I see is that ex4 can hold ACLs, but we have EROFS for that now (with some caveats, i.e. EROFS stores change time (
ctime) not modification time (
mtime)). Not that we support setting custom ACLs anyway.
I propose evaluating its removal.
Add a deprecation warning when using ext4+squashfs.
Remove ext4+squashfs creation from
Remove dm-snapshot handling from mkinitcpio/mkinitcpio-archiso>.