fix: removes listeners when app is reloaded on ios

[fadi-george]

Description

One Line Summary

• addresses this comment ([Bug]: Problem with addEventListener removeEventListener #1610 (comment)) where when app is reloaded, the old listeners arent properly removed

Bug:
https://drive.google.com/file/d/1xryp5XAyJEfz7ZogrS5fQPK-mALf5Iyh/view?usp=drive_link

Fix:
https://drive.google.com/file/d/1Uz_lrnhXHSs0S4vgp9FP_9oXBKady-wg/view?usp=drive_link

Details

• updates event emitter to mimic logic from RNOneSignal java code where I use static instance and call removeHandlers + Observers on the old instance.

Motivation

When doing a reload on the terminal or devtools window, previously any added listeners would just linger so for each reload you would seen an extra log.

Manual testing

Update OSDemo to have:

  useEffect(() => {
    console.log('Initializing OneSignall');
    OneSignal.Debug.setLogLevel(LogLevel.Debug);
    OneSignal.initialize(APP_ID);
  }, []);

  useFocusEffect(
    useCallback(() => {
      const eventMethod = (event: NotificationWillDisplayEvent) => {
        console.log('Event listener called');
        let notification = event.getNotification();
        const data = notification.additionalData as {
          refresh_messages: string;
        };
        console.log('Data:', data);

        if (data?.refresh_messages === 'true') {
          console.log('Preventing default');
          event.preventDefault();
        } else {
          event.getNotification().display();
        }
      };

      OneSignal.Notifications.addEventListener(
        'foregroundWillDisplay',
        eventMethod,
      );

      return () => {
        console.log('Removing event listener');
        OneSignal.Notifications.removeEventListener(
          'foregroundWillDisplay',
          eventMethod,
        );
      };
    }, []),
  );

Run bun run ios in the example project.
Send a test notification to some test subscription.
Click on the react-native terminal.
Should see 1 log per notification.

I also tested w/ additional data (refresh_messages like in issue report). Prevent default should work.

Affected code checklist

• Notifications
  • Display
  • Open
  • Push Processing
  • Confirm Deliveries
• Outcomes
• Sessions
• In-App Messaging
• REST API requests
• Public API changes

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
  • If it is hard to explain how any codes changes are related to each other then it most likely needs to be more than one PR
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have included test coverage for these changes, or explained why they are not needed
• All automated tests pass, or I explained why that is not possible
• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
  • Simplify with less code, followed by splitting up code into well named functions and variables, followed by adding comments to the code.
• I have reviewed this PR myself, ensuring it meets each checklist item
  • WIP (Work In Progress) is ok, but explain what is still in progress and what you would like feedback on. Start the PR title with "WIP" to indicate this.

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