Bouncy Castle Sk-EdDSA / Sk-Ed25519 Support

[atlEdP]

Description

Recently in 2.15 PR #639 (SSHD-988) was implemented so that we can remove dependancy on net.i2p

However the security key variant (specifically usage of SkECDSAPublicKeyEntryDecoder.java and SkED25519PublicKeyEntryDecoder.java) are not included in this change, and still require net.i2p. This means if we use sk we cannot move off net.i2p to Bouncy Castle.

Suggest to update the sk keys to also have support for Bouncy Castle.

Motivation

We cant truly remove net.i2p which has a security weakness if we utilise sk keys

Alternatives considered

No response

Additional context

No response