Specify latency threshold for Fastest IP

### Problem Description

When two popular public resolvers such as Google Public DNS and Cloudflare DNS are used, it can be that Google returns results in a low ping, say ~5ms.

But Cloudflare DNS takes an extra 200ms to reply and returns IPs that are ~40ms away.

### Proposed Solution

The ability to specify a threshold. When it receives the first query and determines that it is >= threshold, it can return the result to the client and close connections for the other queries sent.

The latency would be different for ICMP and HTTP pings, of course.

E.g. 5ms ICMP latency or 12ms HTTP latency would be sensible for servers peered in the same region.

### Alternatives Considered

Fastest IP feature as is right now.

### Additional Information

This feature request could be further expanded to reduce queries to servers while utilizing the Fastest IP feature in the following (ideal) manner:

1. Send queries to the first listed server.
2. If latency of IPs returned is within the threshold, return records to the client, otherwise repeat with the next listed server.