Templates: Add stop_strings meta param

Adding the stop_strings var to chat templates will allow for the
template creator to specify stopping strings to add onto chat completions.

Thes get appended with existing stopping strings that are passed
in the API request. However, a sampler override with force: true will
override all stopping strings.

Signed-off-by: kingbri <bdashore3@proton.me>

endpoints/OAI/app.py

@@ -508,7 +508,10 @@ async def chat_completion_request(request: Request, data: ChatCompletionRequest)
     if isinstance(data.messages, str):
         prompt = data.messages
     else:
-        prompt = format_prompt_with_template(data)
+        # Compile the prompt and get any additional stop strings from the template
+        # Template stop strings can be overriden by sampler overrides if force is true
+        prompt, template_stop_strings = format_prompt_with_template(data)
+        data.stop += template_stop_strings
 
     disable_request_streaming = unwrap(
         config.developer_config().get("disable_request_streaming"), False