[button] Allow receiving focus when `disabled`

Summary 💡

focusableWhenDisabled prop for UnstyledButton has been recently implemented (#32090). The docs claim:

Similarly to the native HTML element, the ButtonUnstyled component can't receive focus when it's disabled. This may reduce its accessibility, as screen readers won't be able to announce the existence and state of the button.

The focusableWhenDisabled prop lets you change this behavior. When this prop is set, the underlying button does not set the disabled prop. Instead, aria-disabled is used, which makes the button focusable.

This should be used whenever the disabled button needs to be read by screen readers.

The same reasoning should be applicable to the MUI Button and Checkbox components

Examples 🌈

See https://mui.com/base/react-button/#focus-on-disabled-buttons

Motivation 🔦

Make <Button disabled /> and <Checkbox disabled> accessible