Add tests for sigmoid_focal_loss and generalized_box_iou_loss

[datumbox]

🚀 The feature

The sigmoid_focal_loss and generalized_box_iou_loss ops are not currently tested. We should create the necessary unit-tests that check the validity for multiple input types.

[oke-aditya]

This will also help folks working on Ciou ad Diou loss. cc @abhi-glitchhg @yassineAlouini

@YosuaMichael I can work on this if you like :)

Reference tests fvcore
https://github.com/facebookresearch/fvcore/blob/main/tests/test_giou_loss.py

[yassineAlouini]

Thanks @oke-aditya for the link.

[YosuaMichael]

Hi @oke-aditya thanks for the offer! Is there anything urgent that need this test?

Currently I actually do this task for the sake of learning (since I am new and it would be good to touch as many part of the code as possible), hence I would like to do this issues myself if possible, however it would take more times.

[oke-aditya]

Oh! Ok no problem @YosuaMichael and congratulations for your new job at Meta. Feel free to do at your pace.

[YosuaMichael]

This issue is done with #5783 and #5792