Describe the bug

Charts provide next-to-no information to screen readers.

Expected behavior

Provide a robust structure that can accommodate more chart info being added to it.

Implementation details

Turn <canvas role="img" /> into a more robust representation:

<figure>
	<canvas role="presentation">
		<dl class="visually-hidden" {...ariaProps}>
			<dt>Chart type</dt>
			<dd>{chartType}</dd>
		</dl>
	</canvas>
	<Legend />
</figure>

• This structure may seem a little overkill but the ultimate goal is something in the vein of this PoC so it sets up a good foundation.
• Note, the aria-* props moved from the <canvas /> to the <dl />
• I'd recommend tackling this after Allow pasing labelling props to <canvas> element #1096, Allow passing description props to <canvas> element #1097, and Add chart type to chart label #1098 otherwise it's too much structure for too little info