Carousel accessibility improvements

Created by: ffoodd

Carousels might be improved, or at least it worths the try:

• WAI ARIA carousel best practices
• WAI Carousel Tutorial

Required

• Add a play/pause button
• Focus the selected item
• Disable prev/next controls when data-bs-wrap="false" and stopped at one end

Nice to have

• Progressive enhancement: adding prev/next buttons and indicators through JS
  • maybe at least drop them when JS is disabled?
• Announce the current item using live region: that seems a bit too much IMHO, but hey, suggesting
• Pause on hover/focus
• Hide transitioning elements from ATs: not quite sure of the current behaviour though, might already be the case.

Docs:

• Add link to WAI Tutorial, maybe? https://www.w3.org/WAI/tutorials/carousels/

Relates to #22549 (closed)