Mapping from `image_id` to image files is missing in saved samples

[sissiok]

When adding "export_batches": true to scenario in Armory configuration json file, image samples and three json files for predictions and ground truth are saved. However, in the json files, only image_id is saved and the mapping from image_id to the image filename is missing. As a result, it is unable to know which image the prediction or ground truth is associated with.

Also, the predictions and ground truth saved in the json files are list and not complete COCO format (dict with mapping and other ancillary information). As a result, it can not be directly loaded with tools like FiftyOne.