Auto scroll on widget

[jimpatrick]

When IntroStepBuilder is not in viewport (not visible) Flutter Intro not scroll on widget like showcaseview.

If you wanna handle this issue, please check it in showcaseview:
https://github.com/SimformSolutionsPvtLtd/flutter_showcaseview/blob/441ca78882a9413839b6797887cdc085488d2444/lib/src/showcase.dart#L615

[ehsandevs]

same issue