ChatOptions.ToolMode doesn't enable require non-function tools

With ToolMode, you can specify that no tools should be used, any tools should be used, at least one tool should be used, or a specific tool must be used. But for the last one, it's limited only to function tools. With other kinds of tools becoming available, like web search, systems are starting to let you require that these tools be used, but there's no way to do that today via ToolMode.