Pull request: all: support more $dnsrewrite rr types

Merge in DNS/adguard-home from 2102-dnsrewrite-2 to master

Updates #2102.
Updates #2452.

Squashed commit of the following:

commit b41e57731b4f276e97202e172fa400067174653d
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Dec 22 20:40:56 2020 +0300

    dnsforward: improve naming

commit 70b832ce969d8cdcf4224d221e5e1e2057fba6ee
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Dec 22 19:36:21 2020 +0300

    all: support more $dnsrewrite rr types

internal/dnsfilter/dnsrewrite.go

@@ -7,8 +7,8 @@ import (
 
 // DNSRewriteResult is the result of application of $dnsrewrite rules.
 type DNSRewriteResult struct {
-	RCode    rules.RCode              `json:",omitempty"`
 	Response DNSRewriteResultResponse `json:",omitempty"`
+	RCode    rules.RCode              `json:",omitempty"`
 }
 
 // DNSRewriteResultResponse is the collection of DNS response records