Rust port of unishox2

[kokroo]

Hi,

I ported unishox2 to Rust. There's a no_std version too, to run on microcontrollers. I also created interop tests between the C and Rust ports. It is memory safe as well. Everything works perfectly so far, to my knowledge.

Do you think you could take a look at it as well before I publish it @siara-cc ?