feat(quickjs): add quickjs sample

quickjs/src/main.rs

@@ -0,0 +1,14 @@
+use quick_js::Context;
+
+fn main() {
+    let context = Context::new().unwrap();
+
+    let value = context.eval("1 + 2").unwrap();
+    println!("js: 1 + 2 = {:?}", value);
+
+    context.add_callback("myCallback", |a: i32, b: i32| a + b * b).unwrap();
+    let script = r#"   var x = myCallback(10, 20);  x;    "#;
+
+    let value = context.eval(script).unwrap();
+    println!("js: callback = {:?}", value);
+}