Introduce Possibility to Abort Event

Up till now, any exception e.g. thrown in Geant4 would be a ModuleError exception that ends the run without calling even finalize(). To be a bit more graceful but also more flexible, I suggest introducing a AbortEventException that stops processing the current event, to mark it as complete and to move on.

The effect is that no modules further down the simulation chain are called. I still have to ensure that this also works in the way e.g. the ROOTObjectWriter currently works and we don't get hickups. But since everything is parallel already ™️ this should be fine - the event is still marked as finished in the thread pool.

This also would allow us to define our own (per-module) criteria for aborting events, (cc)-ing @hwennlof for ideas such as very large energy depositions that might cause OOM down the line.