Add dataset titles to data sets

[kspohlman]

The axises on charts, as well as the column heads for the accessible tables need labels. This is to add the dataset names/titles to be displayed on both chart axises and table headers.

[rheubach]

@Stamates I think this issue is related to the placeholder you and I found the other day. @tmecklem We will need to prioritize this issue if we want our data tables to work for accessibility readers.