[numpy] Add unary-ufunc tests for `erf` variants (#47155)
Summary:
Adding Unary Ufunc Test entry for `erf` variants.
We use scipy functions for reference implementation.
We can later update the tests once these functions will update integer input to float.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47155
Reviewed By: ngimel
Differential Revision: D25176654
Pulled By: mruberry
fbshipit-source-id: cb08efed1468b27650cec4f87a9a34e999ebd810
