[JIT] BC shim for TorchBind classes (#35240)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35240
This makes it so that if we have an old serialized TorchBind class, we don't try to load it in and instead rely on the ClassType that's in memory.
ghstack-source-id: 100703946
Test Plan: buck test mode/dev-nosan //caffe2/torch/fb/predictor/model_repo/tests:ai_infra_representative_model_shard_6_test -- 'RepresentativeModelTest\/ShardedRepresentativeModelTest\.RunModel\/0'
Reviewed By: zdevito
Differential Revision: D20605681
fbshipit-source-id: 5403f68937f822914c701d9c80573f0b4a93e83b
