llama: Add option to merge gate and exp weights (#19139)

llama: Add option to merge gate and exp weights (#19139)

* llama: Add option to merge gate and exp weights

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <redacted>
* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <redacted>
* update constants.py

* add gate_up for the all MoE models

* convert: simplify merge tensor condition

* update constants.py

* reduce number of models, add create_tensor_gate_up helper

---------

Co-authored-by: Sigbjørn Skjæret <redacted>