Explain `test.py`'s `NotImplementedError`s (#1913)
Summary:
This helps the user know why a test was skipped and therefore if it was skipped erroneously.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1913
Reviewed By: davidberard98
Differential Revision: D49461985
Pulled By: xuzhao9
fbshipit-source-id: 70ed393cbf4b99f0fe0fdb8d0b96323981b27bb5
