Pull request: all: upd dnsproxy, fix test, minor imp

Merge in DNS/adguard-home from upd-dnsproxy to master

Squashed commit of the following:

commit 52365328a4c653b0d3bf6d11d8f66a3bf8e0f402
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Jun 10 18:49:50 2021 +0300

    all: rm debug mod replace

commit b29e3cffc5dfa58951a9d819a196e588d26dd887
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Jun 10 18:46:22 2021 +0300

    all: upd dnsproxy, fix test, minor imp

internal/dhcpd/nullbool_test.go

@@ -8,7 +8,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestNullBool_UnmarshalText(t *testing.T) {
+func TestNullBool_UnmarshalJSON(t *testing.T) {
 	testCases := []struct {
 		name       string
 		data       []byte