Allow converting parameters of nn.Module to complex dtypes (#44788)
Summary:
This PR makes it possible to cast the parameters of nn.Module to complex dtypes.
The following code works with the proposed changes.
```python
In [1]: import torch
In [2]: lin = torch.nn.Linear(5, 1).to(torch.complex64)
In [3]: lin(torch.zeros(3, 5, dtype=torch.complex64))
Out[3]:
tensor([[-0.1739+0.j],
[-0.1739+0.j],
[-0.1739+0.j]], grad_fn=<AddmmBackward>)
```
Fixes https://github.com/pytorch/pytorch/issues/43477.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44788
Reviewed By: zou3519
Differential Revision: D24307225
Pulled By: anjali411
fbshipit-source-id: dacc4f5c8c9a99303f74d1f5d807cd657b3b69b5
