Unpopulated DIDDoc Verification Method keys in did:sov resolution

[gmulhearn]

https://github.com/hyperledger/aries-vcx/blob/main/did_core/did_methods/did_resolver_sov/src/resolution/utils.rs#L106C9-L106C54

The DIDDoc returned from .resolve of the did_resolver_sov crate does not have verification methods set in line with the spec.

https://sovrin-foundation.github.io/sovrin/spec/did-method-spec-template.html#crud-operation-definitions

My reading of the spec is that you're meant to do the following for verification methods:

• read ledger for NYM
• add 2 default keys to verificationMethod array: did:sov:...#key-1 & did:sov:...#key-agreement-1
• add did:sov:...#key-1 as a reference in the authentication and assertionMethod arrays
• add did:sov:...#key-agreement-1 as a reference in the keyAgreement array

e.g.:

{
...,
 "id": "did:sov:HR6vs6GEZ8rHaVgjg2WodM",
  "verificationMethod": [
    {
      "type": "Ed25519VerificationKey2018",
      "id": "did:sov:HR6vs6GEZ8rHaVgjg2WodM#key-1",
      "publicKeyBase58": "9wvq2i4xUa5umXoThe83CDgx1e5bsjZKJL4DEWvTP9qe"
    },
    {
      "type": "X25519KeyAgreementKey2019",
      "id": "did:sov:HR6vs6GEZ8rHaVgjg2WodM#key-agreement-1",
      "publicKeyBase58": "3mHtKcQFEzqeUcnce5BAuzAgLEbqKaV542pUf9xQ5Pf8"
    }
  ],
  "authentication": [
    "did:sov:HR6vs6GEZ8rHaVgjg2WodM#key-1"
  ],
  "assertionMethod": [
    "did:sov:HR6vs6GEZ8rHaVgjg2WodM#key-1"
  ],
  "keyAgreement": [
    "did:sov:HR6vs6GEZ8rHaVgjg2WodM#key-agreement-1"
  ],
}

Whereas we are returning:

{
...,
"id": "did:sov:E8GUCXah1MrW4NtxRxiDzt",
  "verificationMethod": [
    {
      "id": "did:sov:E8GUCXah1MrW4NtxRxiDzt",
      "controller": "did:sov:E8GUCXah1MrW4NtxRxiDzt",
      "type": "Ed25519VerificationKey2018",
      "publicKeyBase58": "89v9CRHEtKigUj6H4uPjc7pZ6H8RUvawp7zdD6iyyff7"
    }
  ],
}

Also note that this is a somewhat trivial fix, other than computing the #key-agreement-1 key. That will require a cryptographic conversion from the Ed25519 base58 pubkey to X25519 base58 pubkey