[DAR-5903][External] Do not skip duplicate video sub-annotations for keyframes

[JBWilkie]

Problem

This is an issue that was introduced by DAR-5605

It happens due to some deduplication logic. We parse the annotation frame-by-frame and check if the state of sub-annotations has changed. If it has, we include them in the annotation payload. If it doesn't, we do not

This is fine, since if attributes are left out of the payload entirely, backend doesn't wipe them for that frame. However, DAR-5605 fixed a bug where we weren't representing the transition from some attributes to no attributes correctly. It did this by including attributes: [] in the required places. Unfortunately, we also needed to add a check that only did this for keyframes. Not doing this causes BE to wipe the attributes for that frame

Solution

Do not skip duplicate video sub-annotations for keyframes

Changelog

Fixed edge case when importing attributes on video annotations

[linear]

DAR-5903 BUG: Attribute values lost for non-keyframe frames when exporting and re-importing video annotations