onnxruntime

Initial release of Vitis-AI Execution Provider (#3771)

* Initial release of Vitis-AI Execution Provider

* Add documentation, fix for onnxruntime::Model changes and use stringstream instead of file dump for model passing

* - Add Vitis-AI docker file
- Add online quantization flow Vitis-AI execution provider
- Fix remarks

* - Add fatal error build message for Vitis-AI cmake build on Windows
- Fix pep8 issue in build.py
- Add Vitis-AI execution provider example in docs

Co-authored-by: Elliott Delaye <elliott@xilinx.com>
Co-authored-by: Jorn Tuyls <jornt@xilinx.com>
Co-authored-by: Jorn Tuyls <jtuyls@users.noreply.github.com>