Marshalled managed exceptions should be considered unhandled exceptions by the debugger

[rolfbjarne]

The debugger should consider (at least by default) marshalled managed exceptions as unhandled exceptions, and break.

This has become more important with .NET, where we've enabled exception marshalling by default.

A managed exception may now do the following:

• For iOS and tvOS: get converted into an Objective-C exception, which may end up aborting the process (without the debugger breaking).
• For Mac Catalyst and macOS: get converted into an Objective-C exception, which AppKit swallows and goes on its merry way (without the debugger breaking).

Neither are good scenarios, so we should look into what needs to happen to make the debugger break when an exception is marshalled (it's possible runtime changes will be needed).

Ref: dotnet/maui#7176

[rolfbjarne]

I wonder if we can just call mono_debugger_agent_unhandled_exception like Android does:

https://github.com/xamarin/xamarin-android/blob/1d24421106f5a07b7c150c4390e7d722fe4e618d/src/native/monodroid/monodroid-glue.cc#L837