COCO export performance can be improved

[zhiltsov-max]

Currently, we convert all the values in COCO exporter (convert_instance() etc.) info primitives for builtin json library compatibility. However, we rely on orjson, for dumping, and it natively supports numpy and some other value types. It looks like these conversions could be optimized or at least reviewed, as they can take a significant portion of export time, especially for masks and polygons with big number of points.