Experiment with recursive resolver support

[ameshkov]

Relevant:

• https://github.com/semihalev/sdns/tree/master/middleware/resolver
• https://github.com/rolandshoemaker/solvere
• https://github.com/miekg/unbound
• https://github.com/coredns/unbound
• https://github.com/tenta-browser/tenta-dns