[Feature] Build HAT lights

[dlech]

The Raspberry Pi Build HAT has a two-color LED (red/green). This should serve as the status indication light like on other hubs.

This will be similar to EV3 which also has only 2 colors instead of 3, so we can use that code as a reference. We won't need the the dual LED part, but we will need a new PWM driver that calls into the Pico SDK.

https://github.com/pybricks/pybricks-micropython/blob/9cd476f2b359100c799d1091ba03c29e8bcb0538/lib/pbio/platform/ev3/platform.c#L99-L137

We will also need to figure out how and where to do the pin mux to select the PWM function for the output pins. The official firmware just uses these as GPIOs so can't control the brightness.