sends all mqtt "request" messages over the serial and received serial messages back on mqtt "response" topic
mosquitto_pub -t '/dimmer/request' -m "{\"all\":100}"
{"all":100}- switch on
- red: waiting wifi
 - blue: waiting mqtt
 - green: mqtt connected
 - off: response from STM32
 
 - button press
- green: status requested
 - off : response received and forwarded