[Model] Add elementwise_affine to RMSNorm and re-enable weights loading tracker for Mamba

[Isotr0py]

This PR is a following PR for #10456

• This PR introduces elementwise_affine to RMSNorm, just like pytorch implementation, which could be used to handle unlearnable RMSNorm layer without Parameter initialization.
• This PR also enables the weight loading tracker for Mamba, which is disabled in [Bugfix] Fix Mamba model initialization and MLP Speculator weights loading #10456.

[github-actions]

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[Isotr0py]

Just curious: can we also gain performance improvement from a rms_norm kernel without weight multiply for elementwise_affine=False?