Update fvde2john.py for removable drive support

[holly-o]

Added metadata block decryption and parsing to support FileVault on removable drives

[solardiz]

Thank you! I cannot properly review this for its actual functionality as I'm not familiar with the problem it solves, but it looks reasonable to me.

Maybe also add a NEWS entry?

@exploide Would you like to take a look as well?

[exploide]

@exploide Would you like to take a look as well?

I'm neither familiar with the file format nor do we have sample files (these would be quite large anyway and difficult to store I guess). But from skimming over the code, I think it's fine.

As long as @holly-o tested the code and also ensured it still works with non-removable media, I think this is a great addition!

[solardiz]

nor do we have sample files (these would be quite large anyway and difficult to store I guess)

Maybe these wouldn't necessarily be too large for inclusion in john-samples, @holly-o? If so, we'd appreciate a PR against that repo. Thanks!

Also, I think a NEWS entry is needed.