feat: support option to scroll when there is a large number of menu i…

[supriome]

Make a PR to solve problem of issue 165 when there is a large number of menu items and you want to scroll it.

But there some other problem need to solve, first is setPosition function, I set it to accept an event which type define is any that to get currentTarget of submenuItem when subMenuItem onMouseEnter. It works for mouseEvent, but I've noticed that there another keyboard event need to handle which I don't know how to deal with.

So maybe someone can take it and finish this.