[Modular] Add no_inherit_decorators and fixup wrong RoPE related inheritances

[Bissmella]

Fixes #46399

What does this PR do?

Several attention classes inherit @use_kernelized_func(apply_rotary_pos_emb) from their parent
but override apply_rotary_pos_emb with a version that has no @use_kernel_func_from_hub decoration.
When use_kernels=True is set, kernelize() tries to register the raw function in _hidden_kernels
as an nn.Module and crashes with a ValueError.

The root cause is in replace_class_node() in modular_model_converter.py, when a modular class
defines no decorators of its own, the converter falls back to the parent class decorators, blindly
propagating @use_kernelized_func even when the underlying function has no kernel backing.

Affected models: qwen3_next, qwen3_5, glm4_moe, glm4v_moe, moonshine, laguna

This PR introduces a general-purpose @no_inherit_decorators sentinel in utils/generic.py.
When placed on a class in a modular file, it signals the converter to drop all parent class
decorators for that class. The dummy decorator itself is stripped from the generated output and doesn't
appears in the final modeling_*.py files.

The fix is intentionally general, this decorator propagation problem is not limited to kernels
and could affect other decorators in the future.

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Who can review?

@vasqu, @drbh, @Cyrilvallez

[vasqu]

Thanks @Bissmella, this is a bit more important so I went ahead and took a bit over to also allow the same for functions

[ArthurZucker]

Make sur the tests is a mixin test its a good catch! 🤗

[ArthurZucker]

there's probably a faster way to do this but no worries!

[github-actions]

CI Dashboard: View test results in Grafana

[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: bamba, cohere, cohere2, cohere2_moe, ernie4_5, ernie4_5_moe, ernie4_5_vl_moe, flex_olmo, gemma4, glm, glm4, glm4_moe, glm4v_moe, glm_image, glmasr, helium

[HuggingFaceDocBuilderDev]

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