onnxruntime

Enable selecting custom ops in onnxruntime-extensions. (#8826)

* Enable selecting custom ops in onnxruntime-extensions.

* Move cmake_helper.py.

* Remove over-indented spaces.

* Add doc.

* Remove onnxruntime-extensions from git submodules, and user should pass path of onnxruntime-extensions for build.

* Modify doc.

* Remove argument --enable_onnxruntime_extensions and use --onnxruntime_extensions_path.

* Fix build error.

* Fix build error.

* Use onnxruntime_extensions_path.

* support both submodule and external source folders

* refinement

* Update cgmanifest.json

* Support building onnxruntime-extensions from either git submodule or pre-pulled path.

* Update doc.

* more standard name

* update docs

* add the copyright header

Co-authored-by: Zuwei Zhao <zuzhao@microsoft.com>
Co-authored-by: Wenbing Li <wenbingl@outlook.com>
Co-authored-by: Wenbing Li <10278425+wenbingl@users.noreply.github.com>