[fabric] Update fabric.util.animate type (#45481)
[fabric] Update fabric.util.animate type (#45481)

As per documentation http://fabricjs.com/docs/fabric.util.html#.animate `byValue` is optional. And one of their demos http://fabricjs.com/polygon-animation shows that onChange function can return updated animation value.
dsebastien/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped