Highcharts | Explore a component driven Highcharts theme approach

[tycup]

It's worth exploring whether styledMode: false (default) could offer a simpler architecture. Moving all theming into the Options object means single surface for applying design tokens instead of two. Consumers wouldn't need to import a version-specific Highcharts stylesheet, and setup would come down to using a useChart hook (or a Chart component that wraps it). When we upgrade Highcharts/want to support other versions, we'd only need to check Options API changes rather than also auditing their CSS.

This could involve creating a Chart component wrapper, and reusing the useChart hook for density changes. More details to follow from exploration.

We also prevent some potential confusion/migration issues - styleMode:true disables certain Options object properties (e.g. color within colorAxis)

[joshwooding]

Moved into this sprint as the work will be done between tasks.