This avoids issues with Catch2's handler firing too early, on
structured exceptions that would be handled later. This issue
meant that the old attempts at structured exception handling
were incompatible with Windows's ASan, because it throws
continuable `C0000005` exception, which it then handles.
With the new handling, Catch2 is only notified if nothing else,
including the debugger, has handled the exception.
Signed-off-by: Alan Jowett <alanjo@microsoft.com>
Closes#2332Closes#2286Closes#898