IconButton transitions

[Vehmloewff]

It would be nice if there was a way to have transitions when an icon changes in IconButton.

This would be key to doing that: https://svelte.dev/examples#transition-events.

We could just add another prop:

<IconButton
    icon={[
        { name: 'favorite' },
        { name: 'favorite_outline' }
    ]}
    transition="scale"
    bind:on
/>

Then, every time on is toggled, the old icon will animate out with a scale transition, and the new one will animate it with a scale.