* Add key types for ECDSA and ED25519 with certificates to implement publickey auth with that keys.
* Read public key certificates in OpenSSHKeyV1KeyFile.
* Fix ClassCastException in ECDSAVariationsAdapter.isECKeyWithFieldSize.
* Introduce an integration test for publickey auth with certificates.
* Refactor: merge copy-paste from OpenSshKey*File.java into an util class.
* Add the license to KeyWithCertificateSpec.groovy
* Add the license to OpenSSHKeyFileUtil.java