implement numpy-like functionality isposinf, isneginf (#41588)
Summary:
Related https://github.com/pytorch/pytorch/issues/38349
Numpy-like functionalities `isposinf` and `isneginf` are implemented.
Test-Plan:
- pytest test/test_torch.py -k "test_isposinf_isneginf"
Pull Request resolved: https://github.com/pytorch/pytorch/pull/41588
Reviewed By: ngimel
Differential Revision: D22770732
Pulled By: mruberry
fbshipit-source-id: 7448653e8fb8df6b9cd4604a4739fe18a1135578
