Replace Buffer library

[TimoGlastra]

I've seen several instances where the buffer library we depend on gives weird and inconsistent behaviour. It hasn't been updated in over 5 years.

Since we only use a small part of it, I think we should replace it and find alternatives for the features we support.

The main thing is from/to string to binary. We can rely on a polyfil for React Native focused on performance: https://github.com/maksimlya/react-native-fast-encoder

[berendsliedrecht]

If we only use it for text encoding, and we do not work with 10kB+ of encoded data, we could also look into just implementing it in JS. u8 -> UTF-8 is really simple and perf will not be a big issue on small data sets (going to the native side for small operations is actually a loss in perf).

An issue would be that credo-ts relies on quite some libraries that rely on buffer still. It is just so annoying that Hermes or anything just does not provide a solution out of the box.

[TimoGlastra]

It will be for larger data sets. Since we use it for e.g. SD-JWT and mdOC credentials that have embedded attachments (e.g. pictures). It's not just for text encoding, also for base64/hex. With JSI i think the overhead is really small, and probably more performant than a native solution.

But since react native already implements TextEncoder now, i hope that TextDecoder will also be added relatively soon.

See e.g. for comparisons between JS and native implementations: https://github.com/maksimlya/react-native-fast-encoder.

Reason i suggested replacing the buffer library is that a buffer implementation is quite complex, but if we just use it for transformations we can rely on other APIs I think (base64 <-> Uint8array <-> utf8), and it will be simpler to create a performant API in React Native