[PyTorch Mobile] Support torchbind custom classes in lite interpreter (#51432)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51432
ghstack-source-id: 120976584
torchbind is a convenient way to include custom class to both python and torchscript. CREATE_OBJECT is used to create an object of custom class.
CREATE_OBJECT was not supported by lite interpreter. The major reason was that for custom class directly defined in Python, there's no language parser in lite interpreter. It's still the case. However, for torchbind classes that are defined in C++, a python/torchscript parser is not needed.
This diff is to support the case of torchbind custom classes.
1. The class type can be resolved at import level.
2. If the class is not the supported torchbind class, an error message is provided at export stage. Workaround is also suggested.
3. Unit tests. C++: ```LiteInterpreterTest::BuiltinClass``` is added as an end-to-end test on supported class. Python: ```test_unsupported_createobject``` is changed to ```test_unsupported_classtype``` to test unsupported classes.
Test Plan: CI
Reviewed By: raziel
Differential Revision: D26168913
fbshipit-source-id: 74e8b6a12682ad8e9c39afdfd2b605c5f8e65427
