Have rebar3.cmd work on a Windows CMD shell (#151)

* Provide a working rebar.cmd for system that need it

(Windows on non-PowerShell)

* Add tests for recent changes

If the "run" were to fail the job would too

* Check if Rust can find it

test-projects/rust_rebar3_cmd/.gitignore

@@ -0,0 +1,2 @@
+/target/
+main

test-projects/rust_rebar3_cmd/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "rust_rebar3_cmd"
+version = "0.1.0"

test-projects/rust_rebar3_cmd/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "rust_rebar3_cmd"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

test-projects/rust_rebar3_cmd/src/main.rs

@@ -0,0 +1,32 @@
+use std::env;
+use std::process;
+use std::string;
+
+// an example function...
+fn main() {
+    let key = "PATH";
+    match env::var(key) {
+        Ok(val) => println!("{key}: {val:?}"),
+        Err(e) => println!("couldn't interpret {key}: {e}"),
+    }
+}
+
+#[allow(dead_code)]
+fn rebar3_cmd_version() -> Result<String, string::FromUtf8Error> {
+    println!("going for rebar3.cmd");
+    let output = process::Command::new("rebar3.cmd")
+        .arg("version")
+        .output()
+        .expect("error");
+    return String::from_utf8(output.stdout);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        rebar3_cmd_version().unwrap();
+    }
+}