Summary:
Torch Native Runtime RFC: https://github.com/pytorch/rfcs/pull/72
As part of the effort to open source TorchNativeRuntime (or what we call Sigmoid), we are moving the Pytree implementation to torch/:
fbcode/sigmoid/kernels -> fbcode/caffe2/torch/nativert/kernels
Test Plan:
```
buck run fbcode//mode/dev-nosan //caffe2/test/cpp/nativert:c10_kernel_test
```
Differential Revision: D76825830
Pull Request resolved: https://github.com/pytorch/pytorch/pull/156208
Approved by: https://github.com/zhxchen17
