onnxruntime

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.