Merge in DNS/dnsproxy from mv-fastip-to-netip-addr to master

Squashed commit of the following:

commit e74715a22505e3e192e7d021c34ede802926bf23
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Dec 13 18:02:35 2022 +0300

    fastip: imp docs, tests

commit 31fe75affae136d9a3d45a2fc27dc3cda5cdba83
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Dec 13 17:46:09 2022 +0300

    fastip: mv to netip.Addr