A11Y: Skin Tone Picker should be accessible

[comp615]

The Skin tone swatch in the preview bar should be accessible for both ARIA and keyboard navigation. This could be presented as a select menu or similar component.

[nolanlawson]

Starting to look into this. Seems the best design may be:

<button aria-haspopup="true" aria-expanded={!!opened}>
</button>

The challenge here is that the options are currently inside the button (which is a <div> currently). I think we'll have to change it so the HTML is outside of it, with role="menu"