With the new fancy `_pytest.pathlib.import_path()` we can do real
parametrization of the example-script-module code and thus configure
whether the child, parent, or both silently break the IPC connection.
Parametrize the test for all the above mentioned cases as well as the
case where the IPC never breaks but we still simulate the user hammering
ctl-c / SIGINT to terminate the actor tree. Adjust expected errors based
on each case and heavily document each of these.
6c35ba2cb6