Isopoh.Cryptography.Argon2 API

There are three assemblies and their respective namespaces:

1. Isopoh.Cryptography.SecureArray
2. Isopoh.Cryptography.Blake2b
3. Isopoh.Cryptography.Argon2

To do Argon2 hashing, typically, the only calls needed are the static Argon2.Hash() calls to create the hash and one of the static Argon2.Verify() calls to verify the hash.