Add the ability to choose the ONNX runtime execution provider in `ORTModel` (#137)
* added option for onnxruntime execution provider
* formatting
* better description
* changed ort provider to model arguments
* added documentation
* changed ort provider name
* formatting
* remove wrong files
* trigger actions
* added error catch in case the given arguments for cpu-gpu optimization are contradictory
* remove unused files
* correct wrong catch
* styling
Co-authored-by: Felix Marty <felix@huggingface.co>