DOM order should follow keyboardNavigation.order

[oysteinmoseng]

Expected behaviour

Specific use case: If the legend is placed above the chart, setting keyboardNavigation.order will allow tab navigation order to change, but the DOM order should change as well. This impacts screen reader users navigating by virtual cursor.

Actual behaviour

The DOM order of proxy elements is fixed.

Live demo with steps to reproduce

https://jsfiddle.net/oysteinmoseng/nyv6as9f/
Navigating with virtual cursor, the order is data points first, then legend, then menu, while the Tab order is opposite.

[oysteinmoseng]

This will be closed once PR #16124 is merged