Refactor: Consolidate Bounding box Transformation and IoU Calculation Functions

[hglee98]

Description

This PR aims to refactor bbox transformation and iou calculation function.

Closes: N/A

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Change(s)

1. New Module Creation

• Added netspresso_trainer.utils.bbox_utils module
  • Note: Module location may be subject to change after further discussion

2. IOU Metrics Consolidation

• Unified various IOU calculation implementations into a single comprehensive module
• Extended supported IOU metrics:
  • Standard IOU
  • Generalized IOU (GIOU)
  • Distance IOU (DIOU)
  • Complete IOU (CIOU)

3. Introduction of Universal transform_bbox Function

Previous Implementation

Previously, we needed separate functions for each bbox format conversion:

# Old approach - Multiple specific functions
new_bbox = cxcywh2xyxy(original_bbox)
new_bbox = xyxy2cxcywh(original_bbox)
new_bbox = xyxy2cxcywhn(original_bbox, img_size)

New Implementation

# New approach - Single unified function
new_bbox = transform_bbox(original_bbox, "cxcywh -> xyxy")
new_bbox = transform_bbox(original_bbox, "xyxy -> cxcywh")
new_bbox = transform_bbox(original_bbox, "xyxy -> cxcywhn", img_size=img_size)

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[illian01]

LGTM!