fix!: expando-row accessibility

[ppvg]

Warning

This is a breaking change

This PR attempts to address two a11y issues with expando-rows:

1. The expand button's label incorrectly changes between "open details" and "close details", rather than relying on the aria-expanded state.
   • This PR removes the data-open-label/data-close-label behaviour from expando-row.js. This is a breaking change.
   • The docs now instruct the user to use a button label that uniquely identifies the row (e.g. "lorem ipsum details").
2. The relationship between the visible and expandable rows is not clear (Expando row a11y #415).
   • This PR tries to address this by instructing the user to use the headers attribute to link the expanded row's table cell to the corresponding row's header and the "details" column header.

Online preview: https://manon-expando-row-preview.netlify.app/components/table-expando-row

Screenreader example (NVDA 2024.1 + FF 125.0.3):

Closes #415
BREAKING CHANGE: Remove the data-open-label and data-close-label attributes from expando-buttons and replace the button label with one that uniquely identifies the contents of the expando-row (e.g. "lorem ipsum details"). Consult the documentation for further accessibility improvements to the epando-rows.

[ricklambrechts]

Nice that it is possible to add a specific header for the expando row.