[SYS] Externalize utils functions (#2046)

To declutter main.ino code

Co-authored-by: Florian <1technophile@users.noreply.github.com>

main/ZcommonRF.ino

@@ -301,7 +301,7 @@ void RFConfig_load() {
 }
 
 void MQTTtoRFset(char* topicOri, JsonObject& RFdata) {
-  if (cmpToMainTopic(topicOri, subjectMQTTtoRFset)) {
+  if (TheengsUtils::cmpToMainTopic(topicOri, subjectMQTTtoRFset)) {
     Log.trace(F("MQTTtoRF json set" CR));
 
     /*