Description: Refine threading control options and move inter op thread pool to session state.
Added thread_utils.h/cc to centralize the decision around the thread pool size under various conditions.
Motivation and Context
Currently the thread pool size of the parallel executor is hardcoded to 32 for some reason. This PR makes the options to configure the thread pool sizes clearer.
* Mention OrtCreateSessionFromArray in C API doc
* Update perf tool documentation to reflect the new graph optimization enums. Relax constraint for enable_all.
* Update one more doc
* Update onnx test runner documentation
* Add default in the docs