ENH: ctkDICOMobjectListWidget enhancements

ENH: file spin box added

Fix: hierarchical display of dicom objects in the viewer

ENH: Added file size (in KB) in file path label

Fixed the memory leak

Added copy file path to the clipboard and polished UI.

Removed the unused copy constructor and a sylistic change

replaced QSlider and QSpinBox with ctkSliderWidget and some stylistic modifications

Stylistic changes

Stylistic changes