Add Blake3 support

[httpjamesm]

Summary
Brief explanation of the feature.

Orion currently supports Blake2b hashing through

    let digest = orion::hash::digest(data).unwrap();

which uses Blake2b-256. However, Blake3 is 7x faster wazuh/wazuh#15632.

Basic example
If the proposal involves a new or changed API, include a basic code example. Omit this section if it's not applicable.

I propose adding Blake3 through another function to prevent breaking old code. Maybe orion::hash::digest_blake3?

**Motivation**
Why are we doing this? What use cases does it support? Will it be used anywhere?

It would greatly increase performance of the digest function and allow for variable output sizes, such as 16 bytes and up.

[brycx]

Hi @httpjamesm

Thanks for bringing up this suggestion! I'm definitely not opposed to supporting BLAKE3.

Whether or not it should be the default in the high-level API can be discussed, once we get closer to providing an actual implementation. I'm not a big fan of adding orion::hash::digest_blake3 specifically, as anything in the higher-level modules is intended to incur the least amount of decision making from the user, so I'm tending strongly towards keeping it at a single primitive there.

In either case, we need to provide it in the hazardous module as well.

Is a BLAKE3 implementation something you're interested in working on?

[httpjamesm]

Possibly. Just taking a quick look at the code and I had a few questions:

1. Is it acceptable to simply include the blake3 package and essentially "remap" the existing hazardous hash functions to blake3 functions?
2. I see blake2b_core here. Is that a public crate?

[brycx]

1. We normally try to avoid this. Orion is intended as an alternative to other crates, with a focus on a trimmed-down dependency tree. So we normally provide concrete implementations from Orion directly.

2. No, that's part of the mod.rs file here:

   orion/src/hazardous/hash/blake2/mod.rs

   Line 26 in 39d57ba

   pub(crate) mod blake2b_core {