AppSwitch does not provide any keyboard accessibility

[roastery-zz]

This code does not work as expected:

<AppSwitch tabIndex="0" variant="pill" color="primary"
  checked={isChecked} onChange={this.handleChange}/>

Actual result:

• tabIndex is rendered on the <input> which has display: none.
• This does not work in any browser I've tested, the control is skipped entirely in the tab order.

Desired result:

• tabIndex should be rendered on the wrapped <label>.
• Keyboard support per ARIA checkbox guidelines should be implemented (pressing Space or Enter should toggle the switch)