Add `_enable_recursive_script` to try to script all Python functions (#19578)
Summary:
Stack from [ghstack](https://github.com/ezyang/ghstack):
* **#19578 [jit] Try to script all Python functions**
This adds the `torch.jit._enable_recursive_script` context manager, which will try to compile any Python functions it sees. It's hidden behind an internal context manager for now since it's incomplete (doesn't work for script_methods/Python submodules). If it can't compile the Python function it outputs an error.
](https://our.intern.facebook.com/intern/diff/15386727/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19578
Pulled By: driazati
Differential Revision: D15386727
fbshipit-source-id: 4e308f67677b8e9fccfc525a91bb2f4585062048
