pytorch

11a40410 - pybind11 type_caster for at::Generator and custom RNG python test (#34774)

pybind11 type_caster for at::Generator and custom RNG python test (#34774) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/34774 This PR provides pybind11's `type_caster<at::Generator>` that allows mapping `at::Generator` instance returned from user-defined method to python `torch::Generator`, defined as `THPGenerator ` c++ class. This allows 1) defining custom RNG in c++ extension 2) using custom RNG in python code. `TestRNGExtension.test_rng` shows how to use custom RNG defined in `rng_extension.cpp` Test Plan: Imported from OSS Differential Revision: D20549451 Pulled By: pbelevich fbshipit-source-id: 312a6deccf8228f7f60695bbf95834620d52f5eb