### 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
* based on design document & following InferenceSession's run
implementation, implemented TrainingSession.runTrainStep
### Motivation and Context
* Adding web bindings for training
#### Related work
* #16521 allowed for training artifacts to be built
* #17333 added interfaces for training
* #17474 allowed for training package to be built + added training
backend to web package
* #17891 implementation for createTrainingSession on the TypeScript side
**[SHOULD BE MERGED IN BEFORE THIS PR]**
---------
Co-authored-by: Yulong Wang <7679871+fs-eire@users.noreply.github.com>
Co-authored-by: Ashwini Khade <askhade@microsoft.com>
