PROBLEM
Sometimes users want to be able to scroll left side of the visual indepent from the right and vice versa. Like it is possible currently. But sometimes they will want to be able to scroll synchroneosly.

SOLUTION
We will add a new Button to the visual GUI (bottm right, above "Matchrate highlighting" that enables "synchronous scrolling".
When it is enables, scrolling one visual (if both are visible) will scroll the other visual in sync.

The button should be stateful for the user, remembering what she/he selected last.

The scrolling will calculate from the scroll-height of the scrolled visual taking the zoom-level of the scrolled and the visual to scroll into account. Also, we cannot scroll on the "onscroll" event but we will need to add an interval after which the scroll-position will be synchronized (sync on scroll will cause performance issues)

FRONTEND-TESTING

Apart from testing the feature there should be a short roundtrip to check the localizations of the visual since the localization was reworked to follow our modern format. To check is the In-Context Font Management and the Annotations UI