Refactor: Optimize annotate method in BoxAnnotator for performance and scalability

[suyashw]

• Precomputed colors for detections to eliminate redundant function calls.
• Leveraged NumPy for batch processing of bounding box coordinates.
• Simplified annotation loop to reduce computational overhead.
• Improved code clarity by minimizing repetitive checks and type assertions.
• Enhanced scalability for handling large-scale image annotation tasks.

[CLAassistant]

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[SkalskiP]

@suyashw thanks a lot for your interest in supervision. @suyashw / @soumik12345 have any of you measured annotator performance before and after that change?