Is your feature request related to a problem? Please describe.
GridSplit stack up all the split patches in a new dimension, which makes sense; however, for some use cases like the classification-based pathology tumor detection, we want to treat each of these patches as a separate image, not add new dimension and batch them together via data loader.

Describe the solution you'd like
It seems that the best way to solve this situation is to add an option for split patches in the PatchWSIDataset, so it can split the region into sub-patches and treat them like separate images.