Pull request: all: simplify dnssec logic

Closes #3904.

Squashed commit of the following:

commit 5948f0d3519299a1253e388f4bc83e2e55847f68
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Dec 13 17:53:40 2021 +0300

    querylog: imp

commit 852cc7dbdb495a17ff51b99ab12901b846f8be09
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Dec 13 17:44:41 2021 +0300

    querylog: fix entry write

commit 9d58046899f35162596bfc94fe88fa944309b2fd
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Dec 13 16:45:56 2021 +0300

    all: simplify dnssec logic

internal/querylog/decode_test.go

@@ -34,6 +34,7 @@ func TestDecodeLogEntry(t *testing.T) {
 			`"CP":"",` +
 			`"Answer":"` + ansStr + `",` +
 			`"Cached":true,` +
+			`"AD":true,` +
 			`"Result":{` +
 			`"IsFiltered":true,` +
 			`"Reason":3,` +
@@ -81,8 +82,9 @@ func TestDecodeLogEntry(t *testing.T) {
 					},
 				},
 			},
-			Upstream: "https://some.upstream",
-			Elapsed:  837429,
+			Upstream:          "https://some.upstream",
+			Elapsed:           837429,
+			AuthenticatedData: true,
 		}
 
 		got := &logEntry{}