Describe the bug

We're seeing updates to the generated UI elements despite setting ActionsConfig.allowUpdate to false (which is the default when instantiating FirebaseAiContentGenerator without configuration).

To Reproduce
N/A

Expected behavior
Setting ActionsConfig.allowUpdate to false should prevent the generator from updating surfaces.

Additional context
The current FirebaseAiContentGenerator implementation seems to make the value of configuration.actions.allowUpdate irrelevant because configuration.actions.allowCreate should always be true?

      if (configuration.actions.allowCreate ||
          configuration.actions.allowUpdate) ...[
        SurfaceUpdateTool(
          handleMessage: _a2uiMessageController.add,
          catalog: catalog,
          configuration: configuration,
        ),
        BeginRenderingTool(handleMessage: _a2uiMessageController.add),
      ],

For what is worth, what we're trying to achieve is that generated interface elements are only added "forward", but never removed or updated, because we feel that interface elements being updated on the spot or disappearing is going to confuse users.

Thanks!