[Core feature] Kubeflow TensorFlow Training Operator Evaluator

[Future-Outlier]

Motivation: Why do you think this is important?

The TFJob task config doesn't contain an element for evaluators which is part of the TFJob spec.
I want to make it optional.

Goal: What should the final outcome look like, ideally?

TFJob task config contains evaluator and it is optional.

Describe alternatives you've considered

No.

Propose: Link/Inline OR Additional context

No response

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes