model : Maincoder-1B support (#18534)

* Add Maincoder model support

* Removed SPM model vocabulary setting and MOE related GGUF parameters
Removed trailing spaces from maincoder.cpp

* removed set_vocab

* added new line

* Fix formatting

* Add a new line for PEP8

src/llama-arch.h

@@ -122,6 +122,7 @@ enum llm_arch {
     LLM_ARCH_MISTRAL3,
     LLM_ARCH_MIMO2,
     LLM_ARCH_LLAMA_EMBED,
+    LLM_ARCH_MAINCODER,
     LLM_ARCH_UNKNOWN,
 };