Expose is_signed for dtype (#29511)
Summary:
Changelog:
- Expose is_signed for torch.dtype by modifying torch/csrc/Dtype.cpp
- Allow half, bfloat16 and bool to also been "known" by the isSignedType function
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29511
Test Plan:
- Add tests in test/test_torch.py
Closes https://github.com/pytorch/pytorch/issues/29475
Differential Revision: D18439030
Pulled By: albanD
fbshipit-source-id: 4b1f9da70c1c8dfd0a5bc028b6936acd1c64af47
