Refactor models/export.py arguments

[glenn-jocher]

@SkalskiP @kalenmike @fcakyon PR allows export() to be python-callable now.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Refactoring YOLOv5 model export code for better readability and maintainability.

📊 Key Changes

• Refactored command-line interface into a standalone export function with clearly defined arguments.
• Cleaned up the argument handling by removing argument parsing from inside the exported model code to the main block.
• Ensured assertions and variables are correctly adapted to the new function parameters.
• Improved readability by organizing the code and removing excessive comments.

🎯 Purpose & Impact

• The refactor facilitates code use and maintenance, making it easier for developers to use export features programmatically. 🛠️
• It enhances code clarity for new contributors or users trying to understand the export process. 👀
• There should be no direct performance impact on model export, but the user experience may improve due to cleaner code organization. 📈

[glenn-jocher]

/rebase