Extract the functionality for scrolling the tab carousel.

This creates a TabCarouselScrollManager which handles scrolling of
carousel tabs up when the user scrolls one of the two list views.

This extracts a common copy in preparation for changing it to handle the
switching between scrolled tabs.

Bug: 5123933
Change-Id: I8741140b4770173ca33ea5a9baddb7862c5cf7f5