EDDSA: Add public key resolution with certificate fallback and extend test coverage

[olszomal]

Pull Request Type

• Bug fix
• New feature
• Code style / formatting / renaming
• Refactoring (no functional or API changes)
• Build / CI related changes
• Documentation
• Other (please describe):

Related Issue

Issue number: N/A

Current Behavior

• EdDSA tests were incomplete.
• Public key extraction relied on CKO_PUBLIC_KEY only.
• No fallback to CKO_CERTIFICATE.
• Minor test and initialization inconsistencies.

New Behavior

• Public key is resolved in order:

1. CKO_PUBLIC_KEY (CKA_EC_POINT)
2. CKO_CERTIFICATE (DER X.509 parsing)

• Added Ed25519/Ed448 provider tests covering both paths.
• Improved internal handling and test correctness.

Scope of Changes

• EDDSA public key resolution logic
• New Ed25519/Ed448 provider tests
• Test fixes and minor internal cleanup

Testing

• Existing tests
• New tests added
• Manual testing

Additional Notes

License Declaration

• I hereby agree to license my contribution under the project's license.