* feat(helpers): add method to detect iOS version

* feat(helpers): add a variable to determine whether it is iOS environment

* feat(bscroll): set the default value of variable use-transition

* fix(picker): fix the scrolling problem in iOS13.4 webview

* fix(scroll): fix the scrolling problem in iOS13.4 webview

* docs(ios13.4): added default description of better-scroll parameter