Intel GPU Runtime Upstreaming for Guard (#118523)
# Motivation
According to [[RFC] Intel GPU Runtime Upstreaming](https://github.com/pytorch/pytorch/issues/114842), the 5th runtime component we would like to upstream is `Guard`. We will cover device guard and stream guard in this PR.
# Design
Device guard is used mainly for op dispatcher in PyTorch. Currently, PyTorch already has a device guard abstraction `c10::impl::DeviceGuardImplInterface`. In our design, we will introduce an `XPUGuardImpl` class inherits from `c10::impl::DeviceGuardImplInterface`. Register `XPUGuardImpl` to PyTorch after we implement the device switch management mechanism in `XPUGuardImpl`. Besides, we will introduce `XPUGuard`, `OptionalXPUGuard`, `XPUStreamGuard`, and `OptionalXPUStreamGuard`. They are all following the design of CUDA's counterpart. The corresponding C++ file should be placed in c10/xpu/ folder.
# Additional Context
It is unnecessary to add `Guard` code to PyTorch frontend.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/118523
Approved by: https://github.com/EikanWang, https://github.com/gujinghui, https://github.com/jgong5, https://github.com/malfet
ghstack dependencies: #120315
