Add `cppwinrt` crate and sample

[kennykerr]

Building on #3046, this update introduces the new cppwinrt crate that bundles the C++/WinRT compiler for use in Rust. It just makes it super easy to generate C++/WinRT headers directly from Rust:

[dependencies.cppwinrt]
version = "0.1"

fn main() {
    match cppwinrt::cppwinrt(["-help"]) {
        Ok(output) => println!("{output}"),
        Err(error) => println!("{error}"),
    };
}