Add Animation Support for go.Sankey Plots Similar to go.Scatter and go.Bar

Description

I would like to request the addition of animation support for go.Sankey plots, similar to the functionality available in go.Scatter and go.Bar.

Expected Outcome

The go.Sankey plot should have a parameter in the layout for animations, similar to the updatemenus feature. An example of the desired configuration is shown below:

"updatemenus": [{
    "type": "buttons",
    "buttons": [{
        "label": "Your Label",
        "method": "animate",
        "args": [/* Animation arguments here */]
    }]
}]

This feature would allow users to add animations to go.Sankey plots, enhancing their interactivity and visual appeal.

Comienza comparando el soporte de animación existente para go.Scatter y go.Bar con el punto de entrada go.Sankey, centrándote en cómo se exponen layout updatemenus y el método animate. Se considera completado cuando go.Sankey acepta la configuración de animación equivalente y una prueba de regresión o un ejemplo demuestra los botones y argumentos de animación solicitados.