rust: add binary helper crate for generating raw bindings
This MR is an alternative to !3889 (closed), it introduces the first bits of Rust to eventually support pure-Rust modules. :rust:
This MR mainly adds a binary helper crate that will be used to manually generate the raw bindings.
Creating and generating the bindings will be as simple as invoking cargo run -p vlcrs-sys-generator
and adjusting the source for the new wrappers.
It also adds the relevant files to the .gitignore and creates the src/rust/
Cargo workspace.