model: support youtu-vl model (#18479)

model: support youtu-vl model (#18479)

* Support Youtu-VL Model

* merge code

* fix bug

* revert qwen2 code & support rsplit in minja.hpp

* update warm info

* fix annotation

* u

* revert minja.hpp

* fix

* Do not write routed_scaling_factor to gguf when routed_scaling_factor is None

* fix expert_weights_scale

* LGTM after whitespace fixes

* fix

* fix

* fix

* layers to layer_index

* enum fix

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Co-authored-by: Xuan-Son Nguyen <redacted>
Co-authored-by: Sigbjørn Skjæret <redacted>