Transition schemas to credential specs

[macterra]

Transition from:

    "didDocumentData": {
        "schema": {
            "$schema": "http://json-schema.org/draft-07/schema#",
            "@context": [
                "https://www.w3.org/ns/credentials/v2",
                "https://firstperson.network/credentials/dtg/v1",
                "https://w3id.org/security/suites/ed25519-2020/v1"
            ],
            "$credentialTypes": [
                "VerifiableCredential",
                "DTGCredential",
                "EndorsementCredential"
            ],
            "type": "object",
            "properties": {
                "endorsementType": {
                    "type": "string"
                },
                "endorsementName": {
                    "type": "string"
                },
                "competencyLevel": {
                    "type": "string"
                }
            }
        },
    },

to

    "didDocumentData": {
        "name": "DTG - EndorsementCredential",
        "credentialContext": [
            "https://www.w3.org/ns/credentials/v2",
            "https://firstperson.network/credentials/dtg/v1",
            "https://w3id.org/security/suites/ed25519-2020/v1"
        ],
        "credentialTypes": [
            "VerifiableCredential",
            "DTGCredential",
            "EndorsementCredential"
        ],
        "schema": {
            "$schema": "http://json-schema.org/draft-07/schema#",
            "type": "object",
            "properties": {
                "endorsementType": {
                    "type": "string"
                },
                "endorsementName": {
                    "type": "string"
                },
                "competencyLevel": {
                    "type": "string"
                }
            }
        },
    },