did:peer - IDs in verification methods

[llorllale]

The did:peer VDR is producing docs with incorrect IDs for authentication:

Example

{ 
    "@context": [
        "https://w3id.org/did/v1"
    ],
    "authentication": [
        "#CkPGqALPjt8PFWbYd4WmcNX4Qq3iXdUVq67s3yeh9vxe"
    ],      
    "created": "2020-08-10T16:13:22.45194098-04:00",
    "id": "did:peer:1zQmRtJYm9vMdFd4sedav1nyLjaMQp2BozhvTWkiWNSjbFq3",
    "publicKey": [
        {
            "controller": "#id",
            "id": "#CkPGqALPjt8PFWbYd4WmcNX4Qq3iXdUVq67s3yeh9vxe",
            "publicKeyBase58": "CkPGqALPjt8PFWbYd4WmcNX4Qq3iXdUVq67s3yeh9vxe",
            "type": "Ed25519VerificationKey2018"
        }
    ],
    "service": [
        {
            "id": "#agent",
            "priority": 0,
            "recipientKeys": [
                "CkPGqALPjt8PFWbYd4WmcNX4Qq3iXdUVq67s3yeh9vxe"
            ],
            "routingKeys": null,
            "serviceEndpoint": "http://example.com/didcomm",
            "type": "did-communication"
        }
    ],
    "updated": "2020-08-10T16:13:22.45194098-04:00"
} 

The did-core spec says:

The value of the id property for a verification method MUST be a URI.

... where the structure of URIs is defined in RFC3986:

Each URI begins with a scheme name that refers to a specification for assigning identifiers within that scheme.
....
scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )

---

Note:

• publicKey has been replaced by verificationMethod in did-core: Restructure Core Properties section w3c/did-core#345

[llorllale]

The security vocabulary lists all known verification methods as "unstable" and do not have normative text around the structure of references to verification methods: https://w3c-ccg.github.io/security-vocab/#authentication

[llorllale]

Turns out that normative text around relative DID URLs was recently added to did-core: https://w3c.github.io/did-core/#relative-did-urls

[llorllale]

Because relative URLs are part of the did-core spec, our did:peer VDR is compliant.

But we cannot use relative URLs in a verificationMethod of an LD proof without adding @base to the JSON-LD document's @context.

[llorllale]

The JSON-LD's @context can be inlined or referenced. Currently we only support referenced contexts.