The previous logic just preserved the scroll position on any resize event regardless of if the resize (width or height change) caused the scroll position to get lost or not.
E.g., when the "page scale mode" respected only the width and the resize only changed the window height, it still preserved the scroll position, while the scroll position did not get lost.
There can be cases where when scrolling backward/forward the first/last page never gets visible in the viewport due to a large width/height of another page.
In that case the intersection observer would never trigger and thus, the chapter wouldn't get changed.
By using the Pager, which always takes up the full width/height, this problem will not be possible, since the start/end of the Pager always enters or leaves the viewport.
In case many chapters are rendered, even just the HOC wrapper component re-render due to the context change increases the render time.
Thus, getting rid of these HOC wrapper re-renders by moving the context usage up to the ReaderViewer decreases the render time.
Automatically choose the progress bar position based on the available space.
Previously it was only possible to automatically switch from a horizontal to a vertical position but not the other way around
