[KEYBOARD]: Additional chart data should be available by mouse hover and keyboard navigation

[1Copenut]

Steps to reproduce

1. Log into a Kibana test instance dashboard
2. Mouse over a chart like a time series or pie chart, verify the additional data popover appears
3. Tabbing will skip over the chart and likely land on the chart controls or next panel

Actual Result

• Tabbing passes over the chart without activating the additional data points

Expected Result

• Users can tab into the chart and activate data points by keyboard or pointer device. See https://www.w3.org/WAI/perspective-videos/keyboard/ for a user demonstrating a pointer device to navigate by keyboard.

Meta Issue https://github.com/elastic/elastic-charts/issues/300

Kibana Version: v7.13.0

OS: MacOS Big Sur

Browser: Chrome latest

Relevant WCAG Criteria: Understanding Success Criterion 2.1.1: Keyboard - Level A

[elasticmachine]

Pinging @elastic/datavis (Feature:ElasticCharts)

[elasticmachine]

Pinging @elastic/kibana-accessibility (Project:Accessibility)

[elasticmachine]

Pinging @elastic/datavis (Team:DataVis)

[elasticmachine]

Pinging @elastic/kibana-visualizations @elastic/kibana-visualizations-external (Team:Visualizations)