Change metrics' supported datasets to be read from yaml config file directly instead

[ehuan2]

Currently, the supported datasets are specified by hand in each separate metric class, making it worse for users to modify and add their own dataset. This can be easily fixed by reading from default_datasets.yaml by making the edit:

metric_groups:
  embeddings:
    supported_datasets:
      - SuoDataset
      - GarciaAlonsoDataset
      - MaDataset
    dataset_tags:
      - defaultSuo
      - defaultGarciaAlonso
      - defaultMa

and repeated for each metric group.

This change can be done in the metrics/base.py class.