retire custom form elements (checkbox, radio) in favour of accent-color

[bitstarr]

Since accent-color has wide browser support now, check if the custom interfaces for radios and checkboxes are still relevant.

https://www.matuzo.at/blog/2023/100daysof-day94/

[bitstarr]

Also re read Adrians articles https://adrianroselli.com/2023/05/under-engineered-patterns-for-wcbuf.html

[bitstarr]

there is still a lack of styling options for form elements. have to review later…