Add interactive 2D widgets in context views

Superseeds: !3546 (closed).

It primarely does the same, that is :

• add representation for a 2D equalizer widget in a chart view
• add the Equalizer filter

With some improvements :

• add vtkSMNewWidgetRepresentationProxyAbstract and pqInteractivePropertyWidgetAbstract to prevent code duplication between 2D and 3D widgets.
• add ShowInteractiveWidgets and HideInteractiveWidgets python functions in paraview.simple and it's corresponding tracing, as well as deprecating Show3DWidgets and Hide3DWidgets
• add XML hint WidgetVisibilityLink to allow interactive widget linked to a source with multiple output to only be shown when a specific output port is selected in the Pipeline Browser. The behavior is shown in the following GIF :

Fix: #19293 (closed)
Fix: #20708 (closed)

Needs: vtk/vtk!8965 (merged)