Migrate to ESP-IDF 5.x and Arduino 3.x

[mairas]

The Espressif and PlatformIO are in an unfortunate staring contest wrt. supporting Arduino Core 3 and ESP-IDF 5.x in PlatformIO. As a result, the ESP32 Arduino Core in PlatformIO isn't getting updates or bugfixes which I would like to use in SensESP. Given that a new pioarduino project has emerged to bridge this gap, SensESP should probably adopt it. Using the updated platform requires only a one-liner change in plaformio.ini for the end user, but the changes in the framework itself require some trivial fixes in SensESP itself.

I don't yet know whether it is feasible to try to support both Arduino core versions simultaneously.