Is your feature request related to a problem? Please describe.
Currently, we have a basic default_prepare_batch in engines, it would be useful to add support to prepare extra data besides image and label as our engines already support args and kwargs:
https://github.com/Project-MONAI/MONAI/blob/dev/monai/engines/trainer.py#L181
We have reference implementation in NVIDIA Clara, will reimplement it in MONAI stype.