FQDN resolver for http measurements not allowed

[alexey-yarmosh]

It is allowed in docs but fails the validation:

{
  "target": "jsdelivr.com",
  "type": "http",
  "measurementOptions": {
    "resolver": "cloudflare-dns.com"
  }
}

[MartinKolarik]

I'd say that's more of a docs issue. We support it in DNS because dig does, but I don't think we need it for HTTP.

[jimaek]

Not sure if related but now would #467 work? Maybe we'll add support for this anyway

[MartinKolarik]

No, this would still be just a regular DNS. And in case of #467, dns/http commands would require separate implementations, so I think we'd do it only for dns command too.