feat: add __concurrent/arc-swap

__concurrent/arc-swap/src/main.rs

@@ -0,0 +1,11 @@
+use once_cell::sync::Lazy;
+use arc_swap::ArcSwap;
+
+static TEST_STRING: Lazy<ArcSwap<String>> = Lazy::new(|| {
+    ArcSwap::from_pointee("Hello World!".to_owned())
+});
+
+fn main() {
+    let s = TEST_STRING.load();
+    println!("{}", s);
+}