server: fix streaming crashes (#13786)

* add preludes to content on partial regex match

* allow all parsers to parse non-tool-call content.

* tweak order of <|python_tag|> vs <function= parsing for functionary v3.1 format. still not ideal but hopefully less prone to crash

tools/server/server.cpp

@@ -364,6 +364,7 @@ struct server_task {
             params.oaicompat_chat_syntax.reasoning_format = params_base.reasoning_format;
             params.oaicompat_chat_syntax.reasoning_in_content = params.stream;
             params.oaicompat_chat_syntax.thinking_forced_open = json_value(data, "thinking_forced_open", false);
+            params.oaicompat_chat_syntax.parse_tool_calls = json_value(data, "parse_tool_calls", false);
         }
 
         {