871: nrf/saadc: add type-erased AnyInput. r=Dirbaio a=Dirbaio
872: nrf/usb: prevent user code from constructing a PowerUsb directly. r=Dirbaio a=Dirbaio
PowerUsb must be constructed through `new()` so that it sets up the IRQ.
It must have at least one private field, otherwise user code can construct
it directly with `PowerUsb{}`.
Co-authored-by: Dario Nieuwenhuis <dirbaio@dirbaio.net>