credential ID should be the subject of claims

[gvelez17]

so our whole thing is that we want addressable claims

and so that the ID of a credential is how we link to it

so we want to expose that ID in our database

right now the id is just a serial we define, and we are gonna use that as the subject of claim, that's not really what LinkedClaims are about

-- CreateTable
CREATE TABLE "Credential" (
    "id" SERIAL NOT NULL,
    "context" JSONB,
    "type" JSONB,
    "issuer" JSONB,
    "issuanceDate" TIMESTAMP(3),
    "expirationDate" TIMESTAMP(3),
    "credentialSubject" JSONB,
    "proof" JSONB,
    "sameAs" JSONB,
    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
    "updatedAt" TIMESTAMP(3) NOT NULL,

    CONSTRAINT "Credential_pkey" PRIMARY KEY ("id")
);

we need to do this in a more legit way, where the actual id from inside the json of the credential, can be the subject of a claim, so we need to expose it an index on it