Base64
https://github.com/adamvr/arduino-base64
https://github.com/boseji/rBASE64
https://www.arduinolibraries.info/libraries/base64
https://techtutorialsx.com/2017/12/09/esp32-arduino-base64-enconding/
https://techtutorialsx.com/2018/11/27/esp32-arduino-base64-decoding/
https://forum.arduino.cc/index.php?topic=448942.0