Support doc_string for TorchBind custom classes (#46576)
Summary:
With this PR, users can optionally provide a "doc_string" to describe a class or its method. doc_string for TorchBind classes and methods are stored as `doc_string` properties in `Function` and `ScriptClass`. These `dos_string` properties are then exposed in Python layer via PyBind for doc generation.
Fixes https://github.com/pytorch/pytorch/issues/46047
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46576
Reviewed By: wanchaol
Differential Revision: D24440636
Pulled By: gmagogsfm
fbshipit-source-id: bfa9b270a6c2d8bc769a88fad6be939cc6310412
