Run inference for summarization

Hi @ibeltagy Great work on the paper!

What parameters are specific to running the inference for summarization? I have fine-tuned the `longformer-encdec-large-16384` model on a dataset, and am wanting to test the best model evaluation over the test set.

All that is saved to the output directory currently is `_ckpt_epoch_1.ckpt ` and a folder with some additional metadata.

Apart from `--test` and `--model_path`, are there other obvious parameters that must be passed?

Thanks.