gh-76785: Show the Traceback for Uncaught Subinterpreter Exceptions (gh-113034)

gh-76785: Show the Traceback for Uncaught Subinterpreter Exceptions (gh-113034)

When an exception is uncaught in Interpreter.exec_sync(), it helps to show that exception's error display if uncaught in the calling interpreter.  We do so here by generating a TracebackException in the subinterpreter and passing it between interpreters using pickle.