Add Windows ARM bindings

[CGMossa]

Fixes #190

Current status: This is compiling, but it is not producing the right result as none of the machine are Windows ARM machines, and thus, don't have the right Rtools (with the right Rust) installed.

[yutannihilation]

Sorry, I didn't know it's this tricky.

https://github.com/r-rust/faq#does-rust-support-windows-on-arm64-aarch64

[CGMossa]

Rust doesn't ship with std binaries for these. Somehow, this https://doc.rust-lang.org/cargo/reference/unstable.html#build-std needs to be part of the CI for these new targets.
I have not figured out this.

[CGMossa]

Status: What's missing are the appropriate headers. They must be.. somewhere. If someone wants to take over, please do! I'll give this a break for now.

[CGMossa]

They are here:

if (ARCH == "arm64") {
    core.addPath(`C:\\rtools44-aarch64\\usr\\bin`);
    core.addPath(`C:\\rtools44-aarch64\\aarch64-w64-mingw32.static.posix\\bin`);
 }

mingw variable needs to be corrected to this, when on Windows+Arm

[CGMossa]

Okay, while this may compile. It isn't actually installing Rtools with ARM, or anything like that yet.