onnxruntime

cc779983 - Enable a single build with optimized inference and on device training (#14241)

Enable a single build with optimized inference and on device training (#14241) ### Description Right now prepacking code is not compiled when training is enabled. Our partners want a single build of ort which can do both optimized inference + training on device. This PR enables prepacking code in a training build and controls whether it is enabled or not using already existing session option - kOrtSessionOptionsConfigDisablePrepacking For Inference scenarios - prepacking will be turned on by default and this behavior remains the same after this PR too. For training scenarios - prepacking will be disabled by default and if user explicitly enables it then an error will be thrown. ### Motivation and Context Enable both optimized inference as well as on device training in a single build. For on device training use flag --enable_training_apis.