Merge in DNS/adguard-home from add-stringutil to master
Squashed commit of the following:
commit 4ca9b29356de7d0a162b1e5a6496c691e9751f15
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date: Thu Jul 29 17:29:25 2021 +0300
all: replace aghstrings with stringutil