LoRa GPS TTNMapper based on RP2040

ATTENTION! The lmic library is (as usual) broken. I don't want to fork the lib for a single line fix.

So simply paste the following line into .pio/libdeps/pico/MCCI LoRaWAN LMIC library/src/hal/hal.h at line 16, until I find a more elegant solution:
#include "lmic/oslmic.h"

Uplink payload formatter for TTN Console: Gist

TTNMapper webhook setup tutorial: https://docs.ttnmapper.org/integration/tts-integration-v3.html

TODO: Pinout and docs and stuff