Add parameter to make_dataset.py for running with parameterized pref_name count

[jonlandrum]

Synopsis
The program requires a computer with very generous resources available. If those resources are not available, the program will crash with an error stating such.

Acceptance Criteria

• Add arguments to the file make_dataset.py to accept a pref_name count value, and set the value to 100 by default
• Use this parameter on line 66 instead of hard-coding the expression count > 100

[ikmckenz]

Should use argparse to set the value, look at how --trees is set in src/models/train_structuretomoa.py for guidance.