Rework how fields in the bounding box JSON are represented

[kevinsbarnard]

The bounding box JSON has taken on several metadata fields in addition to the box dimensions (and potential linked image reference). Among others, these include:

• observer
• verifier
• generator

The presence of these metadata in the JSON is unideal for a few reasons. Primarily, the JSON schema is not formally standardized or described, so there is ambiguity in the population and interpretation of these values. In addition, this schema tends to change over time to suit new needs and would benefit from being separated from the core x, y, width, height, and image_reference_uuid fields that describe the bounding box and its source imagery.

We should rework how we are handling these fields. This is part of a larger discussion of how best to structure the bounding box/track information within VARS.

[kevinsbarnard]

Related to mbari-org/annosaurus#14