Add Fake DNS support (#309)

Co-authored-by: Xiaokang Wang <xiaokangwang@outlook.com>
Co-authored-by: loyalsoldier <10487845+Loyalsoldier@users.noreply.github.com>
Co-authored-by: kslr <kslrwang@gmail.com>

app/dns/nameserver_test.go

@@ -7,14 +7,16 @@ import (
 
 	. "github.com/xtls/xray-core/app/dns"
 	"github.com/xtls/xray-core/common"
+	dns_feature "github.com/xtls/xray-core/features/dns"
 )
 
 func TestLocalNameServer(t *testing.T) {
 	s := NewLocalNameServer()
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second*2)
-	ips, err := s.QueryIP(ctx, "google.com", IPOption{
+	ips, err := s.QueryIP(ctx, "google.com", dns_feature.IPOption{
 		IPv4Enable: true,
 		IPv6Enable: true,
+		FakeEnable: false,
 	})
 	cancel()
 	common.Must(err)