fix: Android headless JS timeout (#33044)

Summary:
Fixes #33043 and thereby invertase/react-native-firebase#3955.

The issue arised because when there currently is no available React context, `HeadlessJsTaskService` will create a new one in background and start the task using `onReactContextInitialized` of `ReactInstanceManager.addReactInstanceEventListener`.
https://github.com/facebook/react-native/blob/7ef14af81f3a1532ca1a703da666ea2e5a70a265/ReactAndroid/src/main/java/com/facebook/react/HeadlessJsTaskService.java#L94-L113
The `TimingModule` however is initialized asynchronously, meaning the headless JS is started before its initialization. That's an issue because the `TimingModule` is only run when there is JS code executing (meaning if the application is running or there is a headless task running) - this is checked by registering a `HeadlessJsTaskEventListener` on the `HeadlessJsTaskContext` in `TimingModule.initialize()`.
https://github.com/facebook/react-native/blob/7ef14af81f3a1532ca1a703da666ea2e5a70a265/ReactAndroid/src/main/java/com/facebook/react/modules/core/TimingModule.java#L69-L75
However this event listener is never invoked because the task was started before `TimingModule.initialize()` is called -> `TimingModule.onHeadlessJsTaskStart(...)` is not called and the timer never resumes.

In order to fix this we can just invoke `HeadlessJsTaskEventListener.onHeadlessJsTaskStart(...)` for all currently running tasks when a new listener is added to `HeadlessJsTaskContext`. This call then needs to be `synchronized` as otherwise there's a race condition with `HeadlessJsTaskContext.finishTask(...)` where `onHeadlessJsTaskFinish(...)` could be called before `onHeadlessJsTaskStart(...)`. See the diff for the exact changes.

## Changelog

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[Android] [Fix] - Fixed `TimingModule` related functions for headless JS tasks, eg. `setTimeout`

Pull Request resolved: #33044

Test Plan: I did a local build with the changes and tested the provided example code from #33043 there.

Reviewed By: sshic

Differential Revision: D34006573

Pulled By: dmitryrykun

fbshipit-source-id: d6a821bbd6476ba278c1d8895edb4a0ba16d889e

ReactAndroid/src/main/java/com/facebook/react/jstasks/HeadlessJsTaskContext.java

@@ -61,9 +61,15 @@ private HeadlessJsTaskContext(ReactContext reactContext) {
     mReactContext = new WeakReference<ReactContext>(reactContext);
   }
 
-  /** Register a task lifecycle event listener. */
-  public void addTaskEventListener(HeadlessJsTaskEventListener listener) {
+  /**
+   * Register a task lifecycle event listener. Synchronized in order to prevent race conditions with
+   * finishTask, as the listener will be invoked for already running tasks.
+   */
+  public synchronized void addTaskEventListener(HeadlessJsTaskEventListener listener) {
     mHeadlessJsTaskEventListeners.add(listener);
+    for (Integer activeTaskId : mActiveTasks) {
+      listener.onHeadlessJsTaskStart(activeTaskId);
+    }
   }
 
   /** Unregister a task lifecycle event listener. */