LInux - setDefaultSize needed

[alkebuware]

I'm observing that on Linux await windowManager.setResizable(false); disables our ability to use await setSize(size).

If I reenable resizing, set the size, then disable resizing like below:

await windowManager.setResizable(true);
await windowManager.setSize(size);
await windowManager.setResizable(true);

then the window always reverts to what I set in my_application.cc via gtk_window_set_default_size(window, width, height);

It'd be great if we could add a Linux only setDefaultSize method to the plugin that would allows us to set gtk_window_set_default_size from Flutter, as setSize(size) doesn't work when setResizable(false)