Use Kivy to run Krux on a Raspberry Pi

[ghost]

Kivy opens up a whole new range of devices that Krux can run on, including the Raspberry Pi.

Furthermore, if we do something similar to what SeedSigner is doing with seedsigner-os where we build a custom, stripped-down Linux image to reduce attack surface (and add in secure memory wipe functionality similar to what is done in our MaixPy fork to satisfy my paranoia), then I think "virtualized" Krux on Pi would be effectively as safe as on K210.

Depends on #193

[odudex]

Interesting idea. I have some PIs and a GPIO touch display here, may try it anytime.