Update chat templates (#177)

* Adopting chat template stuff from llama.cpp

* Removing missed conflict marker

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>

Author: ikawrakow

include/llama.h

@@ -1046,6 +1046,8 @@ extern "C" {
                                   bool   add_ass,
                                   char * buf,
                                int32_t   length);
+    // Get list of built-in chat templates
+    LLAMA_API int32_t llama_chat_builtin_templates(const char ** output, size_t len);
 
     //
     // Grammar