These dialogs appear at the top of the annotation list, scroll
them into view if necessary.

The 'scroll-into-view' library is used rather than
Element.scrollIntoView() in order to get smooth animations that are
consistent with how the document is scrolled to selected annotations.

 - Only write to the dialog visibility state in one place
   in AppController.

 - Scroll share and login dialogs into view when corresponding
   link is selected in top bar.

Fixes #3043