SoftwareTrigger is in the wrong module

[kosack]

I just noticed that SoftwareTrigger is in the instrument module, which is not the right place for it. Instrument is for the software model that describes the hardware, not for algorithms. It should go into its own module perhaps.

This could happen during the larger module refactoring in CEP-4 #2489

This is also related to #2606 , where we might want to have a selectable set of algorithms for software triggering.

[GernotMaier]

As a side note, is this really required for prod6 and beyond? There should be flag set describing the trigger type and one would select those events only with LST hardware trigger set (to e.g., suppress the few mono LST trigger in the simulation files)