The Deno.resolveDns surface this resolver needs.
Declared as two call signatures rather than a generic because the real API
is an overload set keyed on the record type: 'SRV' yields records, the
address families yield strings.
resolveDns(query: string,recordType: "SRV"): Promise<DenoSrvRecord[]>
Resolves SRV records.
resolveDns(query: string,recordType: "A" | "AAAA"): Promise<string[]>
Resolves address records.