Arsh/eng 1730 validation set cli support

[azahed98]

Have you read the Contributing Guidelines?

Issue # 1730

Describe your changes

Adds validation files and eval steps

[linear[bot]]

ENG-1730 Validation set - CLI support

Expected behavior, * if --eval_step is non zero, and --validation-file is not provided, return an error. * if --eval_step is zero, and --validtion-file is given, display "warning" saying the eval_step is not given and will run eval every epoch. Run eval every epoch. * if --eval_step is non-zero, and --validation-file is given, run eval every eval_step step * if --eval_step is larger than the training step, and --validation-file is given, no eval is run.

[orangetin]

needs to be rebased