Don't send more ticks than necessary

There are some scenarios where ROHD Cosim will send multiple ticks to the SV simulator back-to-back without any additional value added (e.g. I think if there are no events in a given time). This is a waste of processing, socket communication, and overall simulation time. If it happens frequently it could potentially impact overall simulation duration.

We should avoid sending ticks that aren't necessary.

No files, tests, or entry points are identified. Begin by locating the ROHD Cosim tick-scheduling path and reproduce a case with no events; done means redundant back-to-back ticks are no longer sent without reducing required simulation progress.

Written by the indexing model from the issue text.