implement box_iou_rotated

[cregouby]

Current Situation

there is no way to operate rotated bbox IoU at scale.

Expected Situation

Implement and export the torch/vision ops : https://github.com/pytorch/vision/tree/main/torchvision/csrc/ops :

• Implemented Rotated box iou calculation backend using C++ on CPU.
• Implemented rotated_box_iou function to compute Intersection over Union (IoU) between rotated bounding boxes.
• The public API follows the existing box_iou pattern and supports all three rotated box formats: cxcywhr, xywhr, and xyxyxyxy.

Proposed Test Plan: see (pytorch/vision#9379)
Added TestRotatedBoxIou test class with comprehensive tests:

Core IoU test with 4 boxes (including 45° rotated box) across all three formats

Rotation behavior tests (90°, 180°, 45°, negative angles)

Edge case tests (containment, zero area)

API contract tests (output shape, invalid format, format consistency)