support an operation mode that doesn't dial private IP addresses

There are reports from operators of `Netscan detected` and similar.

This is also present in IPFS nodes, and often comes from attempts to dial peers that have private-space ip addresses
(in this case the data center observed the VM attempting to dial into the `192.168.x.x` and `10.x.x.x` spaces)

* there shouldn't be any multiaddrs returned from the indexer that are in these private address spaces (they are filtered out)
* Perhaps upon connecting to peers as part of identify we learn the other addresses they claim to be listening on, and subsequent dials may attempt those?

this is likely a libp2p configuration tweak. we may want help from libp2p stewards to identify what the optimal configuration will be to limit our exposure to triggering this sort of issue.