Move functorch/functorch into `functorch` folder
- Add functorch/CMakeLists.txt that adds `functorch` native python exension
- Modify `setup.py` to package pytorch and functorch together into a single wheel
- Modify `functorch.__version__` is not equal to that of `torch.__version__`
- Add dummy `functorch/setup.py` file for the projects that still want to build it
Differential Revision: [D39058811](https://our.internmc.facebook.com/intern/diff/D39058811)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/83464
Approved by: https://github.com/zou3519
Summary:
Do not build PyTorch if `setup.py` is called with 'sdist' option
Regenerate bundled license while sdist package is being built
Refactor `check_submodules` out of `build_deps` and check that submodules project are present during source package build stage.
Test that sdist package is configurable during `asan-build` step
Fixes https://github.com/pytorch/pytorch/issues/52843
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52908
Reviewed By: walterddr
Differential Revision: D26685176
Pulled By: malfet
fbshipit-source-id: 972a40ae36e194c0b4e0fc31c5e1af1e7a815185