Optional `rich.Progress` progress bar in cli

[jlnav]

Perhaps an (optional) progress bar could be displayed in the command-line, updated as sims (for sim_max) or gens ( for gen_max) get completed.

https://rich.readthedocs.io/en/stable/progress.html

This would be in the main/manager process, and likely updated upon generator work getting created, or simulator work getting retrieved back from the workers.