Provide Tor Hidden Service DNS addresses

For a privacy Service like this it would be very nice to see. May let people allow to connect anonymously and even use it if behind firewall or as a bridge for people have ipv6 only connection with issue of ipv4 resolver connectivity as found in other issue for example add Hiddenservice address like adguard1dns5443.onion as a DNS/-Crypt resolver
Sure DNS is based on UDP by default and this support only tcp. but as you are dnscrypt enabled! Which is great. It works with your server on port TCP with dnscrypt-proxy -T (command line agrument). That works fine on anycast IP by now.
There is already dnscrypt resolvers offering this hidden for few years.

If fearing latency there still is some improvement along default config, first easiest is local dns cache..

https://adguard.com/en/privacy.html#website

> `Information we collect when you use Adguard DNS
>
> When you use Adguard DNS browser sends the following information to our server:
>
> IP-address.
> DNS request containing domain name.
> We, in our turn, do not log or save any information. Since no information is being saved, nothing is sent to third parties.

```
```