Strips out the custom CMake defs in the bouffalo_sdk

TODO:

1. Add other chips
2. Use fully open source post process and flasher
   • flash
   • post process
3. Use more upstream code for the included projects (lvgl, cherryusb, lwip, fs, nuttx,..)
4. RF -- no idea how this works. Post proc and flasher both do something here with binary libs.