feat: add in initial rust folder contents with best guess

Author: 56kyle

{{cookiecutter.project_name}}/rust/Cargo.lock

@@ -0,0 +1,12 @@
+[package]
+name = "{{cookiecutter.project-name}}"
+version = "{{cookiecutter.version}}"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[lib]
+name = "{{cookiecutter.package_name}}"
+crate-type = ["cdylib"]
+
+[dependencies]
+pyo3 = "0.22.0"

{{cookiecutter.project_name}}/rust/Cargo.toml

@@ -0,0 +1,14 @@
+use pyo3::prelude::*;
+
+/// Formats the sum of two numbers as string.
+#[pyfunction]
+fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
+    Ok((a + b).to_string())
+}
+
+/// A Python module implemented in Rust.
+#[pymodule]
+fn {{cookiecutter.package_name}}(m: &Bound<'_, PyModule>) -> PyResult<()> {
+    m.add_function(wrap_pyfunction!(sum_as_string, m)?)?;
+    Ok(())
+}