Current bug behavior

When the FlameGame gets disposed (page closes), it should remove all components of itself (call onRemove() on all the sub-components to let them clear their resources)
First of all, when we close the game page (which contains a game), it does not automatically call remove on the child objects, to do that we need to write the below code manually:

@override
void onRemove() {
  removeAll(children);
  super.onRemove();
}

This onRemove() method on the game that extends FlameGame gets called when the page closes, but when we call removeAll(children);, it adds the components to the lifecycle._removals queue. But it never processes this queue. Because GameWidget is removed from the widget tree and there is no other tick to call lifecycle.processQueues().
So it leads to a memory leak in some components such as FlameBlocListenable because onRemove will never be called and subscription leaks.

Expected behavior

I expect that FlameGame call removeAll(children); under the hood and process the removal queue before the game disposes to allow all sub-components to free their resources in the onRemove() function.

Steps to reproduce

I wanted to put a Zapp link, but it seems Zapp is down at this moment, so there is a main.dart file here.
You just need to add these dependencies to run the reproducible code:

flame_bloc: ^1.8.2
flutter_bloc: ^8.1.2
flame: 1.6.0

Steps:

1. Run the game, then HomePage opens
2. Click on the Play button on the HomePage, then GamePage opens.
3. Click the plus button
4. LeakingCounterComponent.onNewState(1) prints in the screen
5. press the back button
6. MyGame.onRemove() is called, but LeakingCounterComponent.onRemove() didn't call, so it leaked through it's subscription.
7. Click the Play and plus button again
8. Now you see LeakingCounterComponent.onNewState(2) printed 2 times (because there is a leak)
9. press the back button again
10. Click the Play and plus button again
11. Now you see LeakingCounterComponent.onNewState(3) printed 3 times (because there are two leaks)

As a workaround, I wrote the below code:

@override
void onRemove() {
  ...
  removeAll(children);
  processPendingLifecycleEvents();
  super.onRemove();
}

So with this code, LeakingCounterComponent.onRemove() gets called everytime we close the game page

Flutter doctor output

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.7.1, on macOS 13.2.1 22D68 darwin-arm64, locale
    en-US)
[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 14.1)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2021.3)
[✓] IntelliJ IDEA Community Edition (version 2022.2.4)
[✓] IntelliJ IDEA Community Edition (version 2022.3.1)
[✓] IntelliJ IDEA Community Edition (version 2022.3.2)
[✓] VS Code (version 1.76.0)
[✓] Connected device (2 available)
[✓] HTTP Host Availability

• No issues found!