Fix labels to keep them visible for long texts

Problem description:
When we want to annotate long texts, the labels are scrolled out and are not visible anymore.

Solution:
Labels should be fixed to the bottom of the page, to the right of the page etc (depending on the settings); there should be a checkbox be a setting to activate the fixing of labels.

Remark:
This issue is the same as issue #2573 but is still open since 2022. Someone have replied with a code to add in the settings ("sticky" labels), but that functionality should be native.

Start by reviewing issue #2573 and the existing settings approach or code referenced in this issue's comment. Reproduce annotation of a long text, then verify that an optional setting keeps labels fixed according to the chosen position while scrolling.

Written by the indexing model from the issue text.