copy-purge-model-storage-functionality-for-main

[david-thrower]

From #236 , a branch to add functionality to purge model storage

TLDR: Often multiple Cerebros runs will be made with hyperparameter optimization.

• Typically only the best model from each trial is relevant
• This holds up a lot of storage space and bloats the RAM cumulatively as trails progress if workin g in a container without a volume mounted

Non - default / backward compatible functionality to delete the model storage after calling .get_best_model() or can be called discretely.

• Merge in changes on new-hpo-study-ready-to-run #230 for this functionality
• Add a CICD test that verifies the files are deleted when .get_best_model(purge_model_storage=True)
• Ensure CICD tests calling .get_best_model() with this left default do not delete the model files.