Add accessibility attributes

[saibotsivad]

I've been reading through some ARIA docs and realized this component should probably just be a progress element, but if not it at least needs the role=progressbar attribute.

In addition, I need to read through the docs, but there are some ARIA properties (labels, valuenow, etc) that should be set, and some guidance documented on the proper way to place this in a page for screen readers.