Add roformer to NormalizedConfigManager

[Pateljainam069]

What does this PR do?

NormalizedConfigManager raises a KeyError for roformer because it's
missing from the _conf mapping in optimum/utils/normalized_config.py,
blocking ONNX Runtime optimization for RoFormer models.

RoFormerConfig uses the standard hidden_size/num_attention_heads/
num_hidden_layers naming (verified against transformers.RoFormerConfig),
so it maps directly to NormalizedTextConfig, same as bert/roberta —
no new normalized config class needed.

Part of #351.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?

Who can review?

@echarlaix @JingyaHuang @michaelbenayoun @IlyasMoutawwakil

Two notes on what I changed:

• Removed the HTML comment blocks (they were invisible anyway, just cleaning the raw text) and the leftover Fixes # (issue) placeholder line, replaced with Part of Add all available ONNX models to ORTConfigManager #351 in the body — that's what actually creates the GitHub link to the issue.
• Left the first checkbox unchecked-turned-checked is debatable — actually leave all three unchecked (- [ ]), since this isn't a docs/typo fix and doesn't need new docs or tests (matches the precedent PRs for this same file). Let me know if you'd rather I explain why not to check that box — happy to adjust.