model : support for LlamaBidirectionalModel architecture (#18220)

* model: llama-embed-nemotron

* minor: python lint

* changed arch-name

* templated llm_build_llama to be used for both llama and llama-embed arch

convert_hf_to_gguf.py

@@ -8695,6 +8695,11 @@ class NemotronHModel(GraniteHybridModel):
                 raise ValueError(f"Unprocessed experts: {experts}")
 
 
+@ModelBase.register("LlamaBidirectionalModel")
+class LlamaEmbedNemotronModel(LlamaModel):
+    model_arch = gguf.MODEL_ARCH.LLAMA_EMBED
+
+
 @ModelBase.register("BailingMoeForCausalLM")
 class BailingMoeModel(TextModel):
     model_arch = gguf.MODEL_ARCH.BAILINGMOE