Rework native->managed callbacks to allow for managed errors

[nirinchev]

Description

As seen in #1978, if we throw an exception in a managed function called by native, that will result in a pretty hard crash. We should revisit where we invoke managed callbacks from native and figure out whether errors need to be returned and rethrown "somewhere"

Example code that will cause an issue:

realm.Changed += (s, e) =>
{
	throw new Exception("aaa");
};

We should probably design a system where managed callbacks either swallow/log all exceptions or return a pointer to the exception in native, which is then rethrown back in managed at some point.

How important is this improvement for you?

No response