Certifies the OpenID4VP Verifier's signing key for a DNS name, or answers
the certificate already there when it is over that key and not about to
expire.
Parameters
realmId: any
the realm
spec: any
{ dnsName, publicKeyPem, alg, keyAlg }
Returns Promise<any>
a promise of { ok: true, certificate, issued } or
{ ok: false, errors }
Certifies the OpenID4VP Verifier's signing key for a DNS name, or answers the certificate already there when it is over that key and not about to expire.