Implement cxx For Interop Support between C++ and Rust

[simondevenish]

I am looking to utilize Kajiya as the renderer in my custom C/C++ engine.

After doing a fair amount of research on this, the best solution appears to be implementing support for https://cxx.rs/index.html#cxx--safe-interop-between-rust-and-c

I looked at alternatives such as adding FFI, which I deemed was too complex and unstable.