Correct exmple errors (#1208)

This PR fixes errors in two example files related to ROSIDL parsing and action server functionality. The changes address missing module imports and improve code clarity with better numeric formatting.

- Adds missing parser module import in the ROSIDL parse action example
- Updates timer interval from BigInt constructor to BigInt literal notation with explanatory comment

Fix: #1207

Author: minggangw

example/actions/action_server/action-server-defer-example.js

@@ -83,7 +83,8 @@ class FibonacciActionServer {
   handleAcceptedCallback(goalHandle) {
     this._node.getLogger().info('Deferring execution...');
     this._goalHandle = goalHandle;
-    this._timer = this._node.createTimer(BigInt(3000000), () =>
+    // Set timeout period to 3s (in nanoseconds).
+    this._timer = this._node.createTimer(3000000000n, () =>
       this.timerCallback()
     );
   }

example/rosidl/rosidl-parse-action-example.js

@@ -15,6 +15,7 @@
 const rosInstallPath = process.env.AMENT_PREFIX_PATH;
 const packageName = 'test_msgs';
 const packagePath = rosInstallPath + '/share/test_msgs/action/Fibonacci.action';
+const parser = require('../../rosidl_parser/rosidl_parser.js');
 
 parser
   .parseActionFile(packageName, packagePath)