Adds an event handler that runs when the pagination bar is changed.
A pagination bar receives a change event when a user changes the
current page by interacting with the pagination bar.
A change event is not triggered when you change a pagination bar's
current page using the currentPage property.
When a pagination bar is connected to a dataset, changing the dataset's
current page using dataset functions, such
as nextPage(), do not trigger change
events on the pagination bar.
handler(event: Event): void The name of the function or
the function expression to run when the item is ready.