Filtering by protocol stack

The `-p` on the CLI filters results by protocol stack. Not sure yet what the interface around `Resolve()` should be.

```
> madns -p /ip6/tcp/wss /dnsaddr/example.net
/ip6/2001:db8::a3/tcp/443/wss/ipfs/Qmfoo
/ip6/2001:db8::a4/tcp/443/wss/ipfs/Qmbar
```