Merge in DNS/adguard-home from 2179-ipset-subdomains to master
Closes#2179.
Squashed commit of the following:
commit de17caac4c2ea2bc7931f162c6dfa7822a71554f
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date: Fri Jan 29 18:34:46 2021 +0300
dnsforward: imp code, docs
commit e5ab957560bcfba80feac4b72f9b22535ecd4c7d
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date: Tue Jan 26 20:43:31 2021 +0300
dnsforward: imp code
commit 2b84d27b752832885e4896d0e75de2576e2b965b
Author: David Sheets <sheets@alum.mit.edu>
Date: Tue Oct 6 16:34:06 2020 +0100
dnsforward: support subdomain matching in ipset
This is a squash of all commits in #2179.
