Implementation and operator test for STORM optimizer (#36225)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36225
Implemented the [STORM](https://arxiv.org/abs/1905.10018) optimizer operator for dense and sparse cases.
Test Plan:
All newly added unit tests passed using "buck test //caffe2/caffe2/python/operator_test:storm_test".
{F233643713}
Reviewed By: chocjy
Differential Revision: D18702897
fbshipit-source-id: d25eeb492aa2a03c69754d3f076a8239230b3bf4
