Root zone on loopback ("root hints")

### Prerequisites

- [X] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions) and found no answer

- [X] I have searched other issues and found no duplicates

- [X] I want to request a feature or enhancement and not ask a question

### The problem

Some DNS recursive resolvers have longer-than-desired round-trip times to the closest DNS root server. Some DNS recursive resolver operators want to prevent snooping of requests sent to DNS root servers by third parties. Such resolvers can greatly decrease the round-trip time and prevent observation of requests by running a copy of the full root zone on a loopback address (such as 127.0.0.1).

### Proposed solution

Proposed solution:
https://datatracker.ietf.org/doc/html/rfc7706
https://wiki.archlinux.org/title/Unbound#Root_hints

### Alternatives considered and additional information

Related with:
https://github.com/AdguardTeam/AdGuardHome/issues/790