Enabled torch.unique for bool tensors (#28374)
Summary:
Enabled torch.unique for bool tensors.
Tested via unit tests
[issue](https://github.com/pytorch/pytorch/issues/27691)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28374
Differential Revision: D18043413
Pulled By: izdeby
fbshipit-source-id: 295ff03b9b61d33bbd2e05e6211c4f35a0ee23ea
