Add a uniq test module for yunq in rust.

rust/lib/yunq-test/build.rs

@@ -0,0 +1,14 @@
+use std::fs;
+
+fn main() {
+    let input_file = "../../../lib/yunq/test/example/example.yunq";
+
+    println!("cargo::rerun-if-changed={input_file}");
+
+    let input = fs::read_to_string(input_file).expect("Failed to read input file");
+
+    let code = yunqc::codegen(&input).expect("Failed to generate yunq code.");
+
+    let out = std::env::var("OUT_DIR").unwrap() + "/yunq.rs";
+    fs::write(out, code).expect("Failed to write generated code.");
+}