Add FLOPs tracking for nemotronh

[tejasprabhune]

What does this PR do ?

This PR adds FLOPs tracking support for Nemotron-H models (e.g. Nemotron Nano V3).

Issues

List issues that this PR closes (syntax):

n/a

Usage

• You can potentially add a usage example below

# Add a code snippet demonstrating how to use this
nemotron_flops_config, nemotronh = convert_config_to_flops_config(nemotron_pretrained_config)

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• Make sure you read and followed Contributor guidelines
• Did you write any new necessary tests?
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• Did you add or update any necessary documentation? Visit our Document Development Guide for how to write, build and test the docs.

Additional Information

• gated_linear_unit is added to FLOPSConfig as it is needed in _mlp_layer_flops in flops_formulas.py.

[terrykong]

@guyueh1 to review