please add Word Movers Distance with ELMo Embeddings

[bionicles]

It would be nice to add this metric because Word Movers Distance uses information geometry and ELMo uses contextual embeddings. I'm not familiar with all of your metrics so please correct me if there is an existing metric similar to this

[tilmanbeck]

There is an existing github implementation for sth similar: https://github.com/anonymous1001/Eval-Service