Refactor ISIC fine-tuning code and restructure repo

[Vicbi]

Summary

This PR refactors the ViT fine-tuning pipeline for the ISIC 2019 dataset with the following improvements:

• Cleaned and organized import statements.
• Integrated argparse to eliminate hardcoded paths and make the script configurable (dataset name, output directory, resolutions, epochs).
• Modularized metrics computation and GPU memory tracking.
• Improved robustness of AUC calculation and result handling.
• Clarified structure for better maintainability and extensibility.