libview: Keep the scrollbar position when navigating

Maintain the position of the scrollbar to maintain the text position
while navigating from one page to another.

The issue occurs when the visual area is smaller than the actual page.

Closes #16

https://bugzilla.gnome.org/show_bug.cgi?id=318337
7 jobs for issue-16-keep-scrollbar-position in 15 minutes and 13 seconds (queued for 4 minutes and 33 seconds)
latest
Status Job ID Name Coverage
  Build
passed #131024
flatpak

00:09:00

manual #131023
allowed to fail manual
gtk-doc
passed #131020
master

00:05:43

manual #131021
allowed to fail manual
meson
manual #131022
allowed to fail manual
meson-gtk-doc
 
  Deploy
passed #131025
deploy

00:00:29

manual #131026
allowed to fail manual
stop_deploy