Expose moveNext, movePrevious in DriverHook

[BenoitClaveau]

If I want to use an async tour, I cannot call moveNext without having an external reference to the driver instance.

const driverObj = driver({
  showProgress: true,
  steps: [
    {
      popover: {
        title: 'First Step',
        description: 'This is the first step. Next element will be loaded dynamically.'
        onNextClick: () => {
          driverObj.moveNext();
        },
      },
    },
    { popover: { title: 'Last Step', description: 'This is the last step.' } }
  ]
});

Should be replace by this

const myDriverObj = driver({
  showProgress: true,
  steps: [
    {
      popover: {
        title: 'First Step',
        description: 'This is the first step. Next element will be loaded dynamically.'
        onNextClick: (driverObj, element, steps, opts) => {
          driverObj.moveNext();
        },
      },
    },
    { popover: { title: 'Last Step', description: 'This is the last step.' } }
  ]
});