[numpy] add decimals argument to round (#66195)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/65908
Added a new overload instead of updating the current signature. (Had issues with JIT and **maybe** it would have been FC breaking)
TODO:
* [x] Don't compute `std::pow(10, decimals)` for each element.
* [x] Update docs (https://docs-preview.pytorch.org/66195/generated/torch.round.html?highlight=round#torch.round)
* [x] Add tests
* ~~Should we try to make it composite?~~
* ~~Should we add specialized test with more values of `decimals` outside of OpInfo with larger range of values in input tensor?~~
cc mruberry rgommers
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66195
Reviewed By: anjali411
Differential Revision: D31821385
Pulled By: mruberry
fbshipit-source-id: 9a03fcb809440f0c83530108284e69c345e1850f
(cherry picked from commit 50b67c696880b8dcfc42796956b4780b83bf7a7e)
