Fixing pow for special case between cuda tensors and cpu tensors and reframed test cases a tiny bit (#46320)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/46037
I now isolated the special case to be only between cuda tensor bases and cpu tensor exponents. My previous fix was not a complete fix--it fixed some stuff but broke others. The current fix is a more complete fix:
```
In [1]: import torch
In [2]: a=torch.randn(3)
In [3]: b=torch.tensor(2, device="cuda")
In [4]: torch.pow(a,b) #should not work and throws exception now!
In [5]: a=torch.tensor(3, device="cuda")
In [6]: b=torch.tensor(2)
In [7]: torch.pow(a,b) #should work, and now does
In [8]: a=torch.randn(3, device="cuda")
In [9]: torch.pow(a,b) # yeah, that one is fixed and still works
```
To add a test case to reflect the change, I had to modify the existing setup a little bit. I think it is an improvement but would appreciate any tips on how to make it better!
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46320
Reviewed By: malfet
Differential Revision: D24306610
Pulled By: janeyx99
fbshipit-source-id: cc74c61373d1adc2892a7a31226f38895b83066a
