Add ArduinoJson 7 support

[SBKila]

Simple integrate ArduinoJson 7 as default and migrate ArduinoJson 6 managed as compatibility as it was done for ArduinoJson 5 support

[mathieucarbou]

This repo is not maintained anymore. Have a look at: https://github.com/mathieucarbou/ESPAsyncWebServer, which is deployed in Arduino library manager and platformio already