Support JwsVerificationKey2020 for DID public key

[kdimak]

JwsVerificationKey2020 is defined at https://github.com/transmute-industries/lds-jws2020.
Example of the public key definition with type=JwsVerificationKey2020:

{
  "id": "did:example:123#_Qq0UL2Fq651Q0Fjd6TvnYE-faHiOpRlPVQcY_-tA4A",
  "type": "JwsVerificationKey2020",
  "controller": "did:example:123",
  "publicKeyJwk": {
    "crv": "Ed25519",
    "x": "VCpo2LMLhn6iWku8MKvSLg2ZAoC-nlOyPVQaO3FxVeQ",
    "kty": "OKP",
    "kid": "_Qq0UL2Fq651Q0Fjd6TvnYE-faHiOpRlPVQcY_-tA4A"
  }
}

Please note that currently verifier.PublicKey structure is passed to the signature verifiers. In this particular case, Type=JwsVerificationKey2020z and some public key bytes are filled. This could be not enough for Crypto based signature verifier as we don't pass crvandkty` of the JSON Web Key.