config: add async tasks and polling infrastructure

jay-config/src/macros.rs

@@ -16,6 +16,20 @@ macro_rules! config {
     };
 }
 
+macro_rules! try_get {
+    () => {{
+        #[allow(unused_unsafe)]
+        unsafe {
+            let client = crate::_private::client::CLIENT.with(|client| client.get());
+            if client.is_null() {
+                None
+            } else {
+                Some(&*client)
+            }
+        }
+    }};
+}
+
 macro_rules! get {
     () => {{
         get!(Default::default())