add conversion of descriptors to bounding boxes in qwen format

[csiemssen]

• https://huggingface.co/OpenGVLab/InternVL2-8B#grounding-benchmarks

"We use the following prompt to evaluate InternVL's grounding ability: Please provide the bounding box coordinates of the region this sentence describes: {}"

• https://huggingface.co/Qwen/Qwen-VL-Chat/blob/532ee9f5b88bb9dccf13952045e8a8176e0ed9ce/README.md
• https://swift2x-en.readthedocs.io/en/latest/Multi-Modal/qwen-vl-best-practice.html?utm_source=chatgpt.com
• https://medium.com/@levchevajoana/qwen2-5-vl-with-mlx-vlm-c4329b40ab87

Information about box format for qwen is quite limited

https://arxiv.org/pdf/2502.13923