Add blake range codes
Add blake range codes

Blake2s and Blake2b have different initial vectors states for different lengths, this means that for each chosen output length it looks like completely different hash function.

This proposal allocated 64 values for Blake2b and 32 values for Blake2s as those are the ranges the outputs can be chosen from.

The codes will require 3 bytes to write down as varints.
multiformats/multicodec