fix: execute notification center completion handlers on the main thread

[julien-ctx]

Hi Ortto team 👋

While testing push notifications on iOS, I noticed that the app crashes after tapping on a notification. XCode provided a hint pointing to the MessagingPush+AppDelegate.swift file.

It turns out that the completionHandler is being called off the main thread, which seems to cause issues — probably due to a UI-related action like navigating to a specific tab.

I tried wrapping the completionHandler in DispatchQueue.main.async, and that resolved the crash. To be safe, I applied the same change everywhere completionHandler is used.

The fix has been tested and appears to work well on my side.

Happy to help further if needed — let me know if you have a different approach in mind!

[rlemasquerier]

Hello @scrummitch , Rodolphe here, I hope you are doing well :)
@julien-ctx is working with me on the flutter SDK integration. I was also facing the same issue and he found this fix which seems to solve the issue on my side as well.

[scrummitch]

Thank you both @julien-ctx and @rlemasquerier for the PR !