Add MusicBrainz ID generation

[Bloomca]

Description

I already expose TOC, so maybe it is not necessary, but the helper method can be useful. Also it will be possible to implement in pure Rust and cross-platform, so should be a simple task.

[Bloomca]

So in general, it is relatively simple, and TOC is all you need. However, you also need base64 and SHA1. I guess I can put it behind a feature for conditional compilation, but I feel like it is an overkill. I think I'll provide it as an example in the docs, but won't include it in the library itself.