ChatON:Initial go at vicuna chat template in meta.json

Have looked at tokenizer_config.json, jinja file and default
hardcoded template in llama.cpp.

This is also one of the models where a Global BoS is needed.

NOTE: Have taken the liberty to also add a SYSTEM: prefix wrt
system message, even thou default vicuna doesnt seem to need, but
vicuna-orca seems to need, so that both models can be driven from
same chat template config. I am assuming the system prefix should
not create any problem even in default vicuna, however if it does
create a problem one can duplicate the existing vicuna block in
chaton_meta.json and make the system prefix empty in it.

examples/chaton_meta.json

@@ -378,6 +378,35 @@
 		"systemuser-system-has-end": true,
 		"systemuser-1st-user-has-begin": true,
 		"systemuser-1st-user-has-prefix": true
+	},
+	"vicuna": {
+		"global": {
+			"begin": "<s>",
+			"end": ""
+		},
+		"system": {
+			"begin": "",
+			"prefix": "SYSTEM: ",
+			"suffix": "\n\n",
+			"end": ""
+		},
+		"user": {
+			"begin": "",
+			"prefix": "USER: ",
+			"suffix": "\n",
+			"end": ""
+		},
+		"assistant": {
+			"begin": "",
+			"prefix": "ASSISTANT: ",
+			"suffix": "</s>\n",
+			"end": ""
+		},
+		"reverse-prompt": "</s>",
+		"systemuser-system-has-suffix": true,
+		"systemuser-system-has-end": true,
+		"systemuser-1st-user-has-begin": true,
+		"systemuser-1st-user-has-prefix": true
 	}
 
 }