Add ONNX Support for Decision Transformer Model (#2038)
* Decision Transformer to ONNX V0.1
* Decision Transformer to ONNX V0.2
* Update optimum/exporters/onnx/model_configs.py
* Apply suggestions from code review
* Update optimum/exporters/onnx/base.py
* Update optimum/exporters/onnx/model_configs.py
* Update optimum/utils/input_generators.py
* Update optimum/exporters/onnx/model_configs.py
* Apply suggestions from code review
* Update optimum/exporters/tasks.py
* ONNXToDT: changes to order of OrderedDict elements
* make style changes
* test
* remove custom normalized config
* remove unncessary dynamic axes
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Co-authored-by: Ilyas Moutawwakil <57442720+IlyasMoutawwakil@users.noreply.github.com>
Co-authored-by: IlyasMoutawwakil <moutawwakil.ilyas.tsi@gmail.com>
