Metrics

[BaruchG]

What does this PR do?

Ensured all tests are there for object detection metrics and it's not duplicated. Part of the Lightning Bolts cleanup effort.

Part of #839

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests? [not needed for typos/docs]
• Did you verify new and existing tests pass locally with your changes?
• If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

• Is this pull request ready for review? (if not, please submit in draft mode)

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[otaj]

It seems torchvision has these metrics for quite some time already

[otaj]

• https://pytorch.org/vision/0.9/ops.html#torchvision.ops.box_iou
• https://pytorch.org/vision/0.9/ops.html#torchvision.ops.generalized_box_iou

[BaruchG]

Thanks for catching that @otaj, I'll swap them out.