Links used as UI controls that behave like buttons, should be buttons.
- changes the widgets "toggle", "Delete", and "Close" links to buttons
- uses `aria-expanded` to announce the state of the toggle buttons
- increases a bit the clickable area of the toggle
- ensures the "circular focus" doesn't get cut-off in some browsers by centering the toggle arrows
- uses a `<span>` element with an `aria-hidden` attribute to hide CSS generated font icons from assistive technologies
- standardizes on `.toggle-indicator:before` rather than `:after`
- changes two `#f00` reds in `#dc3232`, see #35622Fixes#31476.
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