Add @ignore annotation (#16055)
Summary:
Adds a decorator `torch.jit.ignore` for Python functions that tells the compiler to skip over these Python values, putting a `prim::Error` in their place which always throws an exception when run.
This lets you have Python-only code in your model in an explicit way, which is useful for debugging, and still be able to save/load the model.
Fixes #15815
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16055
Differential Revision: D13797286
Pulled By: driazati
fbshipit-source-id: 29d36776608ec101649a702952fc6ff3c27655b1
