Pull request: dnsforward: stat empty queries

Merge in DNS/adguard-home from 5910-stats-malformed-entry to master

Squashed commit of the following:

commit ea6718daf0d65dc4b13cd08430da7fdeb6f7fd5b
Author: Dimitry Kolyshev <dkolyshev@adguard.com>
Date:   Mon Jun 19 17:34:50 2023 +0400

    all: imp docs

commit 5341c5b351c87556b91a7f692960edc76f44b21a
Author: Dimitry Kolyshev <dkolyshev@adguard.com>
Date:   Mon Jun 19 16:47:13 2023 +0400

    all: docs

commit 1703c421f501484a80ddcf4ca1ba24f71fa5d225
Merge: f56b62490 d26c480d0
Author: Dimitry Kolyshev <dkolyshev@adguard.com>
Date:   Mon Jun 19 16:46:13 2023 +0400

    Merge remote-tracking branch 'origin/master' into 5910-stats-malformed-entry

    # Conflicts:
    #	CHANGELOG.md

commit f56b62490c7033e1d0b620a9cb4ba8de64862de0
Author: Dimitry Kolyshev <dkolyshev@adguard.com>
Date:   Mon Jun 19 14:49:43 2023 +0400

    all: docs

commit be954a8cab950d038c8cf08b95158069fa0747ba
Author: Dimitry Kolyshev <dkolyshev@adguard.com>
Date:   Mon Jun 19 14:44:05 2023 +0400

    querylog: empty queries

commit 0cda309d402156e750c7387e471da6795aa43bd6
Author: Dimitry Kolyshev <dkolyshev@adguard.com>
Date:   Mon Jun 19 14:26:41 2023 +0400

    dnsforward: stat empty queries

internal/querylog/qlog.go

@@ -161,12 +161,15 @@ func (l *queryLog) clear() {
 // newLogEntry creates an instance of logEntry from parameters.
 func newLogEntry(params *AddParams) (entry *logEntry) {
 	q := params.Question.Question[0]
+	qHost := q.Name
+	if qHost != "." {
+		qHost = strings.ToLower(q.Name[:len(q.Name)-1])
+	}
 
 	entry = &logEntry{
 		// TODO(d.kolyshev): Export this timestamp to func params.
-		Time: time.Now(),
-
-		QHost:  strings.ToLower(q.Name[:len(q.Name)-1]),
+		Time:   time.Now(),
+		QHost:  qHost,
 		QType:  dns.Type(q.Qtype).String(),
 		QClass: dns.Class(q.Qclass).String(),