[Feature] Expose common crypto algorithm to decode parts of patterns

[claunia]

Sorry if this is not the proper repo.

I'm right now writing a pattern that has a struct, only a part of the file, encrypted with AES-128, and thinking about the lzma and the hashes thought it would be a good idea.

IV, Key, and other parameters could be taken from other structures, known files, files requested to the user, or directly asked to the user (I think this is what the in variable does? still getting the gist of the language).

As an example you have a pattern for XCI, that could see if prod.keys can be used, if not ask the user for the key, derive everything, decode the PFS0/NCA/so-on and on.

[WerWolv]

I do like the idea though in general. It would again be an ImHex extension and not directly part of the language but I believe it would fit in with the others yeah. I'd be happy to merge a PR implementing it (would be a great first contribution), otherwise I'll probably get around to doing it eventually 👍