JAVA-1764 Update structure of libraries-concurrency module

libraries-concurrency/src/main/java/com/baeldung/quasar/App.java

@@ -0,0 +1,11 @@
+package com.baeldung.quasar;
+
+import co.paralleluniverse.fibers.Fiber;
+
+public class App {
+    public static void main(String[] args) {
+        new Fiber<Void>(() -> {
+            System.out.println("Inside fiber coroutine...");
+        }).start();
+    }
+}