ESP32 with CO2-Sensor Z19B with OTA-Update

• first check if WiFi is aviable - without no progress
• second check if credentials are storred in non-volatile storage (NVS)
  • if not create an access point and get the User and PW -> store them in NVS
• third open Wifi and connect to MQTT - Brocker
• forth send Headerinformations
• start loop
  • with readings to MQTT-Broker
• end loop