Add iso format

[junio256]

First, thank you very much for maintaining this, it has been a life changer using your app!
I don't know if this will be against the app principle, but .ISO is the only format that I commonly find that isn't supported on ouch, afaik.
Since 7z has support to decompress these types of files, I thought that would be a good idea to implement it.

[marcospb19]

Thanks for the issue, I've added the "PR-welcome" label for anyone who wants to pick this up.

I don't know much about .iso tho, so if someone finds a drawback or concern, please tell them.

[junio256]

Extracting is way easier than compacting since it has to implement a ton of features (drawback of following ISO_9660 standard)

Searched through crates.io and there was no sign of an ISO extrator (at least completed), so implementing by hand might be necessary.
For reference, this is 7z C++ files: https://github.com/ip7z/7zip/tree/5b39dc76f1bc82f941d5c800ab9f34407a06b53a/CPP/7zip/Archive/Iso
And a Wikipedia article detailing how it is done: https://en.wikipedia.org/wiki/ISO_9660
I don't have many experience with ISO either but I can try ~

[marcospb19]

Searched through crates.io and there was no sign of an ISO extrator (at least completed), so implementing by hand might be necessary.

Ouch doesn't implement any format-specific packing or unpacking, so we'd need to wait for a crate in the ecosystem.