Simple DNS-server

This is a DNS server WIP POC, built for learning purposes using tutorial by @EmilHernvall at https://github.com/EmilHernvall/dnsguide/

But in C# instead of Rust (coz i'm kind bored of fighting the borrow checker).

Wannabe's:

1. Use Pipelines.Sockets.Unofficial
2. Write benchmarks
3. Structure chapter branches to be hierarchical
4. Better comments
5. Reduce allocations & remove linq etc.