Support logsoftmax with dim != -1 (#30433)
Summary:
PyTorch dim and ONNX axis have different meanings.
ONNX only supports log_softmax with dim = -1. Transpose must be added before and after log_softmax to support other cases.
This requires input rank to be known at export time.
Fixes https://github.com/pytorch/pytorch/issues/17918
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30433
Reviewed By: hl475
Differential Revision: D18723520
Pulled By: houseroad
fbshipit-source-id: d0ed3b3f051d08d46495a7abfa854edd120dca3a
