- Implements the necessary client code for [ed25519 authentication](https://mariadb.com/kb/en/authentication-plugin-ed25519/).
- Add a test directly from the reference implementation to verify it
works.
- A continuation of #1220,
but doesn't use CGO.
- This patch uses filippo.io/edwards25519 to implement the crypto bits.
The standard library `crypto/ed25519` cannot be used as MariaDB chose
a scheme that is simply not compatible with what the standard library
provides.