[a11y] Issue 39: Opinion Group chart lacks semantic descriptions

[kk-slider18]

Description:
Each group in the Opinion Group chart lacks semantic descriptions, making it difficult for screen reader users to understand the data. Proper ARIA attributes or alternative text should be added.

Component/Area: Open Participation page

Source: Screen Reader

Affected Elements: ARIA attributes, alt text

[YumiChen]

Just a thought, there was a related a11y talk, according to which probably we can utilize both:

• alternative texts for the chart
• hidden data tables

The chart is currently not able to be navigated with keyboard, either. Probably we also want to define what to be announced when a group in the chart is focused