DID:SOV DIDDoc does expand shorthand verkey notation for publicKeyBase58

[gmulhearn]

part of this series of issues; https://github.com/hyperledger/aries-vcx/issues/

On sovrin ledgers, it is possible to register a NYM's verkey in an abbreviated form with a tilda prefix (e.g. ~CoRER63DVYnWZtK8uAzNbx). Some indy notes on this here: https://hyperledger-indy.readthedocs.io/projects/sdk/en/latest/docs/getting-started/indy-walkthrough.html#step-3-getting-the-ownership-for-steward-s-verinym.

This abbreviated verkey is also what the ledger returns when you do a get_nym:

    let nym_res = profile.ledger_read.get_nym(&profile.institution_did).await.unwrap();
    println!("{}", nym_res);

{"op":"REPLY","result":{"seqNo":1,"txnTime":null,"data":"{\"dest\":\"V4SGRU86Z58d6TV7PBUe6f\",\"identifier\":null,\"role\":\"0\",\"seqNo\":1,\"txnTime\":null,\"verkey\":\"~CoRER63DVYnWZtK8uAzNbx\"}","dest":"V4SGRU ...

since the did_resolver_sov crate is just using the ledger's returned verkey as the publicKeyBase58 for the DID's didDoc.verificationMethod[0], the DIDDoc ends up looking like:

...,
"verificationMethod": [
    {
      "id": "did:sov:V4SGRU86Z58d6TV7PBUe6f",
      "controller": "did:sov:V4SGRU86Z58d6TV7PBUe6f",
      "type": "Ed25519VerificationKey2018",
      "publicKeyBase58": "~CoRER63DVYnWZtK8uAzNbx"
    }
  ],

This is ofcourse invalid. It should be the responsibility of the did_resolver_sov crate to notice if the get_nym verkey is in it's abbreviated form (tilda prefix), and if it is, then it should transform the NYM+Abbreviated-Verkey into the full Verkey, which can then be set as publicKeyBase58.