Support for Open Image V7 pretrained models (600 classes)

[fcakyon]

Hello, is it easy to support Open Image V7 pretrained Object Detection weights? I am willing to work on such a PR.

Motivation: OI7 is a superior dataset (16M bboxes, 1.9M images, 600 object classes ) compared to COCO (200K images, 80 classes). Moreover, the OI7 dataset is free for commercial use .

Where should be updated other than https://github.com/supervisely-ecosystem/yolov8/blob/master/models/det_models_data.json ?

Example weight url for OI7 pretrained detection model: https://github.com/ultralytics/assets/releases/download/v8.1.0/yolov8m-oiv7.pt (>= v8.1.0)
https://github.com/ultralytics/assets/releases/download/v0.0.0/yolov8m-oiv7.pt (< v8.1.0)