Add device runtime API for the plug-in to register platform python module into torch (#59857)
Summary:
## Motivation
Allow the out-of-tree Pytorch plug-in, for the device type other than CUDA, to add the runtime interface to the `torch` module. The runtime interface of the device can be referred with the device type name in the `torch` module. I.E., `torch.cuda` or `torch.xpu`.
## Solution
- Add a register interface for the plug-in to add the platform python module into `torch` module with the device type name. I.E., The `torch.xpu` can be used to refer the XPU runtime interface after the XPU runtime module is registered with `torch._register_device_module('xpu', xpu_module)` in Intel's XPU plug-in.
## Additional Context
More details about runtime has been discussed in https://github.com/pytorch/pytorch/issues/53707.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59857
Reviewed By: mrshenli
Differential Revision: D29309320
Pulled By: ezyang
fbshipit-source-id: b9802a5f937ddef9e0bdaf2f7692dfe463912fbe
