Resolve "fix(ui): fiducials distance should be visible only on their specific slice"

Description

Closes #1220 (closed)

Currently, the ruler manages the way to add distance on 3D images (on different slices and always visible). However in a 2D+T images context, the restrict_to_current_slice method doesn't work correctly.

If we change the slice, the added fiducials from previous slices are still displayed.

How to test it?

Test on sight_viewer

• You should configure the XML by adding something like this in volume_rendering.xml and in negato2d.xml:

<connect>
    <signal>${imageSeries}/sliceIndexModified</signal>
    <slot>ruler_fiducial_adp/restrict_to_current_slice</slot>
</connect>

Or test an app that already has this configuration.