Pull request: * all: move internal Go packages to internal/

Merge in DNS/adguard-home from 2234-move-to-internal to master

Squashed commit of the following:

commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 12:44:18 2020 +0300

    * all: move internal Go packages to internal/

    Closes #2234.

internal/util/syslog_others.go

@@ -0,0 +1,18 @@
+// +build !windows,!nacl,!plan9
+
+package util
+
+import (
+	"log"
+	"log/syslog"
+)
+
+// ConfigureSyslog reroutes standard logger output to syslog
+func ConfigureSyslog(serviceName string) error {
+	w, err := syslog.New(syslog.LOG_NOTICE|syslog.LOG_USER, serviceName)
+	if err != nil {
+		return err
+	}
+	log.SetOutput(w)
+	return nil
+}