Add flag for including/excluding altConcept in fathomnet-generate

The user should be able to specify if they do or don't want to append the bounding box `altConcept` when generating a dataset. Currently, it works something like:
```
label = box.concept
if box.altConcept is not None:  # we should be able to toggle this behavior from the CLI
    label += " " + box.altConcept
```