mDNS library does not have support for querying host IP addresses

[pilotniq]

Description

The mDNS library is only coded to support lookup of services, and not host IP addresses.

It would be useful to be able to resolve the IP addresses of other hosts on the network which have mDNS names, such as other ESP modules or Raspberry Pis

[devyte]

Closing in view of #5442 with a full rewrite of mdns.