Add pin mappings for Arduino Nano Every
Add pin mappings for Arduino Nano Every

- RX/TX pin is swapped when using the definition for __AVR_ATmega4809__
https://github.com/ngyl88-arduino/FastLED/issues/2
- Pin mappings used came from working branch
https://github.com/FastLED/FastLED/blob/avrmega/platforms/avrmega/fastpin_avrmega.h

FastLED/FastLED,PaulStoffregen/FastLED,PaulStoffregen/FastLED,FastLED/FastLED,FastLED/FastLED,FastLED/FastLED,PaulStoffregen/FastLED