BREAKING CHANGE: chips now follow the [aria toolbar pattern](https://www.w3.org/WAI/ARIA/apg/patterns/toolbar/examples/toolbar/). Chip sets are toolbars and chips are buttons or links. Filter chips are toggle buttons.
What to change:
- Remove `type` attribute from `<md-chip-set>` (you can mix and match chip types!)
- Remove `single-select` from `<md-chip-set>`. Use JS to control filter chips if single selection is required. Radio filter chips will come in a future update.
- Disabled chips CAN be focused with the keyboard if `always-focusable` is set.
- Filter chips no longer dispatch a `"selected"` event. Listen to `"click"` and use `event.target.selected` instead.
- ArrowUp and ArrowDown no longer navigate between chips. These are reserved for chip actions, like dropdown menu chips.
PiperOrigin-RevId: 566352830
