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/aghtest/upstream.go

@@ -135,6 +135,7 @@ func (u *TestBlockUpstream) Exchange(r *dns.Msg) (*dns.Msg, error) {
 	}
 
 	m := &dns.Msg{}
+	m.SetReply(r)
 	m.Answer = []dns.RR{
 		&dns.TXT{
 			Hdr: dns.RR_Header{

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

internal/dhcpd/options.go

@@ -130,5 +130,5 @@ func (p *dhcpOptionParser) parse(s string) (code uint8, data []byte, err error)
 		return 0, nil, err
 	}
 
-	return uint8(code), data, nil
+	return code, data, nil
 }