Adding mDNS service resolver
Using libmicrodns, we could have an API in GIO that can monitor, lookup and resolve service names over mDNS.
This is better for applications than using Avahi's API, as libmicrodns supports macOS and Windows through the same API, and it wouldn't require punching a hole in the sandbox or creating a portal on Linux.
As libmicrodns is a modern library that uses meson, glib could depend on it as a subproject without needing to expose that it's using the library at all.
This new API could be used immediately in: