xiso compression for XEMU

[Lazorne]

XISO

https://xemu.app/docs/disc-images/

is just:

dd if=game-redump.iso of=game.iso skip=387 bs=1M

or

fallocate -c -o 0 -l 387MiB game.iso

But we need to check somehow if the .iso are compressed already as the xbox folder can have both none and compressed .iso