Pull request: all: replace aghstrings with stringutil

Merge in DNS/adguard-home from add-stringutil to master

Squashed commit of the following:

commit 4ca9b29356de7d0a162b1e5a6496c691e9751f15
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Jul 29 17:29:25 2021 +0300

    all: replace aghstrings with stringutil

internal/home/tls.go

@@ -14,7 +14,6 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
-	"reflect"
 	"runtime"
 	"strings"
 	"sync"
@@ -22,6 +21,7 @@ import (
 
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/log"
+	"github.com/google/go-cmp/cmp"
 	"golang.org/x/sys/cpu"
 )
 
@@ -270,8 +270,9 @@ func (t *TLSMod) handleTLSConfigure(w http.ResponseWriter, r *http.Request) {
 	}
 	status = validateCertificates(string(data.CertificateChainData), string(data.PrivateKeyData), data.ServerName)
 	restartHTTPS := false
+
 	t.confLock.Lock()
-	if !reflect.DeepEqual(t.conf, data) {
+	if !cmp.Equal(t.conf, data) {
 		log.Printf("tls config settings have changed, will restart HTTPS server")
 		restartHTTPS = true
 	}