[FEATURE] add the nadam optimizer

[sarthakpati]

Is your feature request related to a problem? Please describe.

The nadam optimizer incorporates nestrov momentum into the Adam optimizer, thus providing potentially better solutions: https://openreview.net/forum?id=OM0jvwB8jIp57ZJjtNEZ

Describe the solution you'd like

PyTorch has this [ref], and it would be good to expose the api through the configuration definition.

Describe alternatives you've considered

N. A.

Additional context

N. A.