Board-local-txt
This is meant to solve a head scratcher. We're likely to want to support a few boards that have their board define as a plain ESP module, like the DFRobot C3 uses ESP32C3_DEV.
See https://github.com/espressif/arduino-esp32/pull/6883#issuecomment-3078867025
Currently it would be a first come first served, but I have a plan... We add a boards.local.txt or platform.local.txt in wippersnapper that provides an extra define for those kinds of boards. We effectively use the extra_flags or board.defines to define -DWS_DFROBOT_ESP32C3, and have a similar entry in platformIO.ini
I've added a new argument to ci-arduino/build-platforms.py for --boards-local-txt which can take an optional file location (or current working directory default), and will attempt to copy that into the correct platform folder after installing the platform.
https://github.com/adafruit/ci-arduino/compare/ci-wippersnapper...ci-wippersnapper-boards-local-txt
Matching tooling PR: https://github.com/adafruit/ci-arduino/pull/217