components/badge23: split up into bsp and stem

The badge23 component is a (historical) mess. We should attempt to split it up into the following pieces:

1. A BSP (Board Support Package) component which implements the lowest-level components of hardware access (possibly using FreeRTOS components where necessary to provide eg. DMA interop).
2. The 'stem', our noise-making-badge logic (which includes the audio system, the graphical system, etc).