Refactor: Implement Test-Time Augmentation (TTA) as a decorator

[hunterhogan]

This change introduces a decorator-based approach for applying Test-Time Augmentation (TTA) during audio source separation. The apply_use_tta decorator encapsulates the TTA logic, allowing for cleaner and more modular code. This enhances code readability and maintainability by separating the TTA implementation from the core source separation logic.

[ZFTurbo]

I prefer to not have decorators inside this project. It's easier to do coding and debugging without them.