Accordion: Adapt native standard

[mfranzke]

Adapt new native standard of using the name-attribute to controled grouped details/summary components.

https://chromestatus.com/feature/6710427028815872

Expected browser support:

• ☑️ Chromium based starting with version 120
• Firefox: version 130, to be got released beginning of September
• ☑️ Safari: started with version 17.2

[mfranzke]

Adding the name-attribute to the accordion-items has only been part of the relevant changes – additionally the accordion component itself would need to generate and insert a unique name-attributes-value for all of its child-elements.