DefaultDnsServiceDiscoverer sorts addresses by bytes which may remove address type precedence ordering

In order to determine uniqueness and use a stable ordering across look-ups `DefaultDnsServiceDiscoverer` sorts the resolved IPs by their bytes. This may ~reserve~ remove the address type precedence order provided by Netty.

Related:
https://github.com/servicetalk/servicetalk/pull/529#discussion_r279537161

Start at DefaultDnsServiceDiscoverer and read the related pull request discussion at #529, especially the concern about sorting resolved IPs by bytes. Determine how to keep stable uniqueness ordering without removing Netty's address-type precedence. Done means lookups remain stable while preserving that precedence.

Written by the indexing model from the issue text.