- Adds the Switch component
- Updates `Selected`, `Selectable` -> `ToggleState`, `Toggleable`
- Adds `checkbox` and `switch` functions to align better with other
elements in our layout system.
We decided not to merge Switch and Checkbox. However, in a followup I'll
introduce a Toggle or AnyToggle enum so we can update
`CheckboxWithLabel` -> `ToggleWithLabel` as this component will work
exactly the same with either a Checkbox or a Switch.
Release Notes:
- N/A
