Hope to add the function of converting json format labels to coco format labels in one click

[Leon-Brant]

Currently, if we have labeled a batch of images in JSON format, we can only re-label the image if we want to save the label to coco format. This is not very convenient for users, i hope the official can add this function, or can also release the script to achieve such a function. I saw that this software script only semantic tags into instance tags, so few scripts seem to be inconsistent with such a powerful software.