Adding Peter's Swish Op ULP analysis. (#42573)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42573
* Generate the ULP png files for different ranges.
Test Plan: test_op_ulp_error.py
Reviewed By: hyuen
Differential Revision: D22938572
fbshipit-source-id: 6374bef6d44c38e1141030d44029dee99112cd18
