Add manual push completion handler support for iOS

Added Display.notifyPushCompletion() to allow applications to manually signal when they have finished handling a push notification on iOS.
This is useful for apps that need to perform background tasks (like playing audio) before the app is suspended.
This feature is enabled by setting the build hint `ios.delayPushCompletion` to `true`.

Author: google-labs-jules[bot]

CodenameOne/src/com/codename1/ui/Display.java

@@ -5154,6 +5154,22 @@ public void screenshot(SuccessCallback<Image> callback) {
         impl.screenshot(callback);
     }
 
+    /**
+     * Notifies the platform that push notification processing is complete.
+     * This is useful on iOS where the app is woken up in the background to handle
+     * a push notification and needs to signal completion to avoid being suspended
+     * prematurely.
+     * <p>
+     * If the {@code ios.delayPushCompletion} build hint (or property) is set to "true",
+     * Codename One will NOT automatically signal completion after the {@link com.codename1.push.PushCallback#push(String)}
+     * method returns. Instead, the application MUST invoke this method manually
+     * when it has finished its background work (e.g. playing audio, downloading content).
+     * </p>
+     */
+    public void notifyPushCompletion() {
+        impl.notifyPushCompletion();
+    }
+
                            /**
      * Convenience method to schedule a task to run on the EDT after {@literal timeout}ms.
      *