Add option to bind mobility model ticks to system clock

[awlane]

Adds parameters 'use_timed_model_mob' and 'timed_model_mob_tick' to mobility model code. When enabled, these will cause mobility ticks to only occur every 'timed_model_mob_tick' seconds as long as the expected number of ticks for this time interval has occurred.

The current behavior does provide a 0.5s sleep time without the plot but does not prevent error from accumulating over time- over 30s, we can see a 100ms divergence from the expected timing of a tick develop when this sleep time is included. This likely varies from system to system, but this in turn means that reproducibility between systems is fraught. This also allows the end user to control this sleep interval and visualize the behavior as it occurs without the plot more easily.