Python binding to set/get CUDA rng state offset (#98965)
Why?
* To reduce the latency of hot path in https://github.com/pytorch/pytorch/pull/97377
Concern - I had to add `set_offset` in all instances of `GeneratorImpl`. I don't know if there is a better way.
~~~~
import torch
torch.cuda.manual_seed(123)
print(torch.cuda.get_rng_state())
torch.cuda.set_rng_state_offset(40)
print(torch.cuda.get_rng_state())
tensor([123, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0], dtype=torch.uint8)
tensor([123, 0, 0, 0, 0, 0, 0, 0, 40, 0, 0, 0, 0, 0,
0, 0], dtype=torch.uint8)
~~~
Pull Request resolved: https://github.com/pytorch/pytorch/pull/98965
Approved by: https://github.com/kulinseth, https://github.com/ezyang
