add printf support to ESP32/8266 and arduino-pico cores

[2bndy5]

resolves #870

I also added the 2 boards to the PlatformIO CI workflow:

1. Node MCU ESP8266 board
2. Adafruit QtPy ESP32-S2 board

This should help us detect compiler warnings and whatnot.

[TMRh20]

Looks good to me, I haven't tested but assume you have. :p

[2bndy5]

I have tested this - it works well. I was just unsure about undefining printf_P on ESP32 core. Seems ok to do so. Compiler will complain if we don't undefine it first.

[2bndy5]

I just got done re-testing this on the following boards:

1. Node MCU (ESP8266-12E)
2. QtPy ESP32-S2
3. QtPy RP2040

All of them can now use printDetails() 🎉

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I should note that the Official Arduino core for the RP2040 Connect will not be able to use printDetails() still. But honestly, users should be encouraged to use the arduino-pico core as it is just better all around.