New TryExcept decorator

[glenn-jocher]

Includes threaded plots for PR and Confidence curves.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

This PR introduces a more structured exception handling and threading decorators to improve robustness and concurrency in YOLOv5.

📊 Key Changes

• Introduced TryExcept class, a context manager and decorator for handling exceptions with custom messages.
• Replaced try_except decorator with TryExcept context manager and decorator.
• Replaced threaded function with a threaded decorator from utils/__init__.py for improved thread handling.
• Improved plotting functions with TryExcept for better error management and threaded for possible asynchronous execution.
• Minor refactoring in plot methods to use the matplotlib object-oriented API.

🎯 Purpose & Impact

• 🛠️ Enhances error reporting by printing custom messages when exceptions occur, resulting in better debugging experiences for developers.
• 🧵 Provides a more elegant way to handle multi-threaded operations, making code cleaner and potentially improving performance.
• 📈 Improves the reliability of plotting methods through structured exception handling, resulting in fewer unhandled errors and better user experience.
• 🧹 Codebase refactoring leads to improved maintainability and sets a precedent for future contributions.