add retain=true in MQTT topic
### Describe the feature request

When try to integrate MQTT topic I check and not see retain=false for all topics, so controller can't received update for topics because don't about it. To fix this need add retain=true in MQTT topic. Can you add it?

### Describe the proposed solution

When try to integrate MQTT topic I check and not see retain=false for all topics, so controller can't received update for topics because don't about it. To fix this need add retain=true in MQTT topic. Can you add it?

### Describe alternatives you have considered to the enhancement

When try to integrate MQTT topic I check and not see retain=false for all topics, so controller can't received update for topics because don't about it. To fix this need add retain=true in MQTT topic. Can you add it?