Accessibility buttons interfere with surrounding form

[adigourdi]

The Accessibility plugin introduces HTML buttons in the clickable elements of a chart

The said buttons don't have a type attribute, and therefore default to type="submit"

This interferes with any form element surrounding the chart(s)

Live demo with steps to reproduce

https://jsfiddle.net/r6g8cny4/

1. Focus on <input>
2. Hit Enter

Expected behavior

The form should submit, or the button should handle the default behavior

Actual behavior

The first accessibility button on the chart (the legend in the demo) gets the event and toggles series visibility

Product version

Highcharts: 10.3.3 (latest)