Add property binding in torchbind (#50670)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50670
This PR adds property support to Torchbind. There are two cases that it needs to work:
**Torchscript**
Inside Torchscript, we don't go through pybind so there is no issue with accessing properties through ClassType.
**Eager Mode**
In Eager Mode, Torchbind creates ScriptObject which we cannot dynamically add (aka access) properties after initializing it. (https://stackoverflow.com/questions/1325673/how-to-add-property-to-a-class-dynamically
) Therefore we created a Python wrapper (ScriptObjectWrapper) around ScriptObject where we can use property method to set properties. By doing so, we can look up wrapped object's property through __getattr__ method of the ScriptObjectWrapper. This logic is inspired from https://github.com/pytorch/pytorch/pull/44324
Test Plan:
test cases in test_torchbind.py
Imported from OSS
Reviewed By: pbelevich
Differential Revision: D26632781
fbshipit-source-id: dd690887cfda0c48ff0d104aa240ce0ab09055bc
