Add support for squashfs version 2

[qkaiser]

Even though it's quite old, some firmwares in our corpus have squashfs v2 images. One example is the Asus NAS M25 firmware image.

The easiest path to support squashfsv2 is to release a dedicated binary from our sasquatch fork. I worked on https://github.com/onekey-sec/sasquatch/tree/modern-squashfs-v2.0-r2 to have a working codebase with version 2 images. What is missing is building the dedicated v2 binary.

Once it's there we can add v2 to the existing squashfs handler :)

[qkaiser]

sasquatch MR to fix a bug in squashfs-tools that blocked us from extracting version 2 and 1 FS: onekey-sec/sasquatch#13

When it's merge I'm ready with the code to make it work in unblob.