Add pybind11 exception translator (#30588)
Summary:
Closes https://github.com/pytorch/pytorch/issues/30027
The idea here is that you can bind a function with `pybind11` in a single line and without modifying the function:
```cpp
m.def("foo", foo, py::call_guard<torch::PyWarningHandler>());
```
Where warnings are handled by the [`call_guard`](https://pybind11.readthedocs.io/en/stable/advanced/functions.html#call-guard) and exceptions are handled by the `pybind11` exception translator. To do this, I have added support for handling C++ exceptions in `torch::PyWarningHandler`'s destructor without setting the python error state before hand.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30588
Differential Revision: D19905626
Pulled By: albanD
fbshipit-source-id: 90c0a5e298b123cc0c8ab9c52c91be4e96ea47c6
