feat: Add llama_model_is_hybrid API call
Also, split llama_model_is_recurrent into llm_arch_is_recurrent in
llama-arch with llama_model_is_recurrent delegating to
llm_arch_is_recurrent. The same split is done for hybird. This is needed
because there are places where the llama_model has not yet been initialized
but we need to check if the model is recurrent (specifically for the
per-layer recurrent check array in hparams).
Branch: GraniteFour
Signed-off-by: Gabe Goodhart <ghart@us.ibm.com>