Add EMD loss
### Feature request

could we import this file for 1d EMD? its like kl div but allows us to better represent ordinal/numeric classes.
https://github.com/TakaraResearch/Pytorch-1D-Wasserstein-Statistical-Loss/blob/master/pytorch_stats_loss.py
is the best option Ive seen online.

### Motivation

I am currently using it locally for ordinal discrete density function approximation.

### Your contribution

I'm not totally sure whats necessary to incorporate it into the currently available options throughout the codebase, but it shouldn't be hard to import it.
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