Support in upstream CMake via enable_language

[tgross35]

There is some very early and informal discussion about potentially adding rust as an official language to cmake - https://discourse.cmake.org/t/enable-language-option-for-rust-cargo/8514, and the very first stage of work actually doing it https://gitlab.kitware.com/Ayush1325/cmake/-/tree/rust.

Are any contributors here able to leave any suggestions / lessons learned on that thread (or here)? I know there are some very open questions about e.g. how to link libstd, which I am sure had to be resolved for Corrosion, and maybe those answers could help feed back to the upstream ecosystem.