feat(charts): Improve accessibility with keyboard interaction

[akashsonune]

• Traverse legend items with arrow keys (custom legend only)
• Select/Unselect legend item with Enter/space
• Tab to move to charts view with tooltip opened
• Traverse through each data point with arrow keys
• Escape to close tooltip
• Use Shift +/- Shift arrows home to operate zoom slider

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Documentation.
Examples.
Dashboards Demo.
Playwright report.

Coverage Reports:

• charts-ng
• dashboards-ng
• element-ng
• element-translate-ng
• maps-ng
• native-charts-ng

[gemini-code-assist]

Code Review

This pull request implements accessibility features for charts, including keyboard navigation for data points, zoom sliders, and legends, as well as ARIA support and live announcements. The review feedback identifies several TypeScript style guide violations regarding the use of the any type and suggests improvements for ARIA label redundancy and legend navigation logic.

[dr-itz]

Focus is barely visible, needs to be in our focus color. Why not just have the focus border around the whole element?

[akashsonune]

Focus is barely visible, needs to be in our focus color. Why not just have the focus border around the whole element?

done. Not sure about focusing the whole element, I see that the other libs like carbon focus just the legend icon. Maybe we can discuss this along with ux