Provide convenience wrappers for adding/reading IPLD blocks of raw bytes

[ranile]

Similar to @helia/strings (and others), I would like to have a package that takes a Uint8Array for add and returns a Uint8Array for get

This is particularly helpful when dealing with files that aren't text files (e.g. images). I want to be able to upload an image as-is without needed the costly conversion to/from base64