Export dynamic unbind/split and __getitem__ (#29136)
Summary:
In ONNX opset 11, a series of sequence ops were added. Operators that are related to Tensor[] in PyTorch can be exported using these sequence ops.
In this PR, unbind/split that produces Tensor[], and __getitem__ that takes Tensor[] as input, are exported correctly to ONNX opset 11.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29136
Reviewed By: hl475
Differential Revision: D18309222
Pulled By: houseroad
fbshipit-source-id: be12c96bf8d0a56900683ef579f1c808c0a1af21
