Flesh out Arduino Serial Shim

The Adafruit driver for the BME680 is written for Arduino and calls various arduino-native functions. We've shimmed some of those in Arduino.h/cpp, but not the Serial class (print and println methods), as those methods have many type overloads so it's not as simple as just calling printf.

This doesn't affect normal operation, but if we wanted to use the BME680_DEBUG option to print debug info from the sensor, we'd need the shim.

Having this would also make it easier to use arduino libraries on other pico projects.

Here's an example of something that could probably be leveraged:
https://github.com/earlephilhower/ArduinoCore-API/blob/master/api/Print.h