Improve the class listing in "Subclassed by"

The list of classes that appears in the "Subclassed by" section of the examples contains a variable number of elements, depending on whether the class or classes demonstrated is/are a superclass of other classes. In some cases, this list can be very long, e.g.
https://itk.org/ITKExamples/src/Core/Common/FilterImage/Documentation.html, and the readability is low.

If possible, some changes might improve the readability and discoverability of the subclasses:
- Avoid the template parameter list, or apply the nice formatting applied to the classes in the "Classes demonstrated" section.
- Make the classes point to their corresponding Doxygen documentation. If not possible, maybe to examples demonstrating the classes if existing.
- If the above are not possible, maybe we can change the whole section for a link to the class hierarchy that is displayed in the Doxygen pages.
- By default, hide the list and just print "Subclassed by" which would expand when clicking.

Use the linked FilterImage documentation as the reproduction case; inspect how its “Subclassed by” section is generated and compare it with the formatting in “Classes demonstrated.” Check the resulting links or collapse behavior against the corresponding Doxygen hierarchy, with improved readability and discoverability in that example as the completion criteria.

Rédigé par le modèle d'indexation à partir du texte de l'issue.