POVPainter: experiment with `adafruit_imageload` and `OnDiskBitmap`

setup a minimal example with  
 [adafruit_imageload](https://docs.circuitpython.org/projects/imageload/en/latest/) and [OnDiskBitmap](https://docs.circuitpython.org/en/latest/shared-bindings/displayio/index.html#displayio.OnDiskBitmap)

and also add this to
https://github.com/adafruit/Adafruit_CircuitPython_DotStar/issues/64#issuecomment-1689309720


