### Description
* implemented lazyResetGrad function
### Motivation and Context
* we are in the process of adding language bindings to enable training
on web
* lazyresetgrad ensures that the gradients are calculated correctly
after the first runTrainStep call
---------
Co-authored-by: Ashwini Khade <askhade@microsoft.com>
### Description
* implemented runEvalStep and runOptimizerStep
* added hasEvalModel and hasOptimizerModel boolean fields in
TrainingSession representation
* added evalInputNames and evalOutputNames fields to
TrainingSessionHandler & TrainingSession
* removed the inputNamesEncoded and outputNamesEncoded fields from
TrainingSessionHandler -- since none of the training methods require the
input names and output names as parameters, there's no need to store
them.
### Motivation and Context
* part of the work for implementing web bindings for training
* previous PR: #18250
---------
Co-authored-by: Ashwini Khade <askhade@microsoft.com>
### Description
* Implemented: `getParametersSize`, `getContiguousParameters`
(equivalent to copyParametersToBuffer), and `loadParametersBuffer`
(equivalent to copyParametersFromBuffer)
* as part of these changes, getParametersSize was added to the
TrainingSession interface so that users know what size buffer to create
for loadParametersBuffer
* The parameters methods in the interface were modified to take in a
Float32Array instead
### Motivation and Context
* part of the work for implementing web bindings for training
* enables federated learning in the web
* previous PR: #18006
---------
Co-authored-by: Ashwini Khade <askhade@microsoft.com>
### Description
Following the design document:
* Added CreateTrainingSessionHandler to the Backend interface
* All existing Backend implementations throw an error for the new method
createTrainingSessionHandler
* Created TrainingSession namespace, interface, and
TrainingSessionFactory interface
* Created TrainingSessionImpl class implementation
As methods are implemented, the TrainingSession interface will be added
to or modified.
### Motivation and Context
Adding the public-facing interfaces to the onnxruntime-common package is
one of the first steps to support ORT training for web bindings.
---------
Co-authored-by: Caroline Zhu <carolinezhu@microsoft.com>
