model : Add support for Arcee AI's upcoming AFM model (#14185)

* Add Arcee AFM support

* Add draft update code

* Fix linter and update URL, may still not be final

* Update src/llama-model.cpp

Co-authored-by: Xuan-Son Nguyen <thichthat@gmail.com>

* Remote accidental blank line

---------

Co-authored-by: Xuan-Son Nguyen <thichthat@gmail.com>

src/llama-arch.h

@@ -77,6 +77,7 @@ enum llm_arch {
     LLM_ARCH_PLM,
     LLM_ARCH_BAILINGMOE,
     LLM_ARCH_DOTS1,
+    LLM_ARCH_ARCEE,
     LLM_ARCH_UNKNOWN,
 };