Change the slideshow's current slide to a specific slide or index.
The changeSlide() function returns a Promise that is resolved when
the slideshow finishes moving from the current slide to the slide
referred to by slideReference.
You can retrieve Slide objects to pass to the
slideReference parameter from your slideshow using the
currentSlide or slides properties.
If passing a number, note that slide indices in a slideshow are zero-based, even though they are numbered starting from 1 in the Editor.
The slide to move to. Either the index of the slide or a Slide from the slideshow.