[FEATURE] automatically set parent dialog with `window.dialog().file()`

[anatawa12]

To open file dialog correctly linked to window, we have to manually link with set_parent like this:

#[tauri::command]
#[specta::specta]
pub async fn some_command(window: Window) {
    let mut file = window
        .dialog()
        .file()
        .set_parent(&window)
        .blocking_pick_folder();
}

However, I think it's better to link dialog to window by default to reduce mistakes

It may needs some trick on traits and/or breaking changes so I think it may be good to have in v3