python <> rust bindings need zero-copy

[verbiiyo]

For any good binding support, we really want to have the frames being passed from ticks between python and xos to be zero-copy. however, after about 3-4 hours of tinkering today, I wasn't able to get #15 to have true zero-copy.

we got very close with the state.frame.buffer conceptual refactor, which is great because now all rust-defined applications benefit from zero-copies (an example of it can be found here in the ball code)

but yeah, rust is having to copy the buffer returned from python into the state.frame.buffer, because every time i try to get python to just simply write directly to the rust buffer, i'm met with a blank screen.

the ideal case is that python would simply modify the buffer in-place without needing to return it like so.