refs https://github.com/TryGhost/Team/issues/1225
When the gif selector is activated we want to scroll as much of the picker into view as possible.
- updated `scroll-into-view` modifier so it can work on bounding rects as well as offsets for those situations where a scroll parent is not the offset parent
- only implemented "off bottom" behavior for now as that's all we need for this use-case
- if the scroll adjustment would mean the top is cut off we readjust so that the top of the element is always visible
refs https://github.com/TryGhost/Team/issues/1225
- added `scroll-into-view` modifier that will scroll an element into view putting it at the top or bottom of the viewport depending on which direction scroll is required
- used the `scroll-into-view` modifier to scroll the highlighted gif into view
