feat: Keypoints in COCO

[makseq]

More info about keypoints in coco: https://cocodataset.org/#format-data

Note: if you label has flag:0 in name, visibility flag = 0. Similar to flag:1 and flag:2. By default it's 2.

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@83ac08c). Click here to learn what that means.
Patch has no changes to coverable lines.

Additional details and impacted files

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  Files             ?       20           
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  Hits              ?      754           
  Misses            ?      966           
  Partials          ?        0           

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[RiccardoMaistri]

does it work?

[makseq]

After careful consideration, we’ve determined that this is more of an improvement than a critical bug. Additionally, it seems to be an outdated request and hasn’t garnered much interest from the community. For these reasons, we will be closing this issue. We will continue developing the converter library as a part of Label Studio SDK.

We appreciate your understanding and encourage you to submit your feedback, questions and suggestions here:
https://github.com/HumanSignal/label-studio-sdk/issues