Add scrollBehavior to various scrollto functions

[fourjr]

Adds a scrollBehavior parameter to all scrollToX functions. The parameter accepts 3 values (auto, instant, smooth) (MDN Docs).

This resolves #20 by setting scrollBehavior to smooth.

[fourjr]

@RobPethick any chance to get this PR merged soon?

[scoelliCollectAI]

@RobPethick ☝️

[megatron-hoa-tran]

While waiting this PR is merged You guys can use like this

scrollBarRef.current.view.scroll({
  left:30,
  behavior: 'smooth',
});
    
scrollBarRef.current.view.scroll({
  top:30,
  behavior: 'smooth',
});