test: Add macOS SwiftUI sample app

[philipphofmann]

Add a sample app for macOS with SwiftUI using the
NSApplicationDelegateAdaptor.

This is required because a customer has this setup and would like to make uncaught NSExceptions work correctly. With this sample app, we can test their setup.

#skip-changelog

[brustolin]

Just one suggestion, I would prefer to have less assets (in this case the icons).
With cocoapod or SPM, our users download all the samples too, the less bits the better.

[philipphofmann]

Just one suggestion, I would prefer to have less assets (in this case the icons). With cocoapod or SPM, our users download all the samples too the less bits the better.

Excellent point. I will update the PR after merging this one: #4461.