Merge in DNS/adguard-home from 2234-move-to-internal to master
Squashed commit of the following:
commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date: Fri Oct 30 12:44:18 2020 +0300
* all: move internal Go packages to internal/
Closes#2234.