net: do not prefer IPv4 addresses during resolution.

Currently, the address resolution family defaults to IPv4. This commit removes that preference, and instead attempts to resolve to a family suitable for the host.

@tjfontaine is this along the lines of what you wanted? This is my first time venturing into the core C++ layer, so forgive me if it's way off.

Closes #7637
I would give an example using the full object, since (anecdotally, at least) code examples tend to pop out to me quicker than the surrounding paragraph text.

```
{
  family: 4, 
  hints: dns.ADDRCONFIG | dns.V4MAPPED
}
```

It might also be good to add some text in the above paragraph to the effect of `See below ("Supported `getaddrinfo` flags") for information about these hint flags.`