Hook up UMLObject::m_TaggedValues in widgets and class options:

umbrello/basictypes.h
- Add namespace ShowStereoType with Enum { None, Name, Tags }.

umbrello/umbrello.kcfg
- In group "Class Options" change entry "showStereoType" to type "Enum"
  with choices "None", "Name", "Tags".

umbrello/optionstate.h
- In class ClassState change type of member showStereoType to
  Uml::ShowStereoType::Enum.

umbrello/optionstate.cpp
- Adjust function ClassState::loadFromXMI1 to changed type of member
  showStereoType.

umbrello/umlwidgets/umlwidget.{h,cpp}
- Change type of member m_showStereotype to Uml::ShowStereoType::Enum.
- At function showStereotype change return type to
  Uml::ShowStereoType::Enum.
- At function setShowStereotype change argument type to
  Uml::ShowStereoType::Enum.
- New function tags() returns stringified m_umlObject->tags().

umbrello/umlwidgets/widgetbase.cpp
- In function slotMenuSelection add deprecation note at case
  ListPopupMenu::mt_{Show,Hide}_Stereotypes_Selection.

umbrello/umlwidgets/classifierwidget.h
- At enum VisualProperty add deprecation note on value ShowStereotype.

umbrello/umlwidgets/classifierwidget.cpp
- Adjust to change in type of OptionState::ClassState::showStereoType
  and UMLWidget::m_showStereotype.  Affect methods:
  - ClassifierWidget(UMLScene *, UMLClassifier *)
  - ClassifierWidget(UMLScene *, UMLPackage *)
  - bool visualProperty(VisualProperty) const
  - void setVisualPropertyCmd(VisualProperty, bool)
  - QSizeF calculateSize(bool withExtensions) const
  - void paint(QPainter *, const QStyleOptionGraphicsItem *, QWidget *)
  - void changeToClass()
  - void changeToInterface()
  - void changeToPackage()
  - bool loadFromXMI1(QDomElement &)
  - void saveToXMI1(QDomDocument &, QDomElement &)

umbrello/umlwidgets/entitywidget.cpp
- In function slotMenuSelection remove case
  ListPopupMenu::mt_Show_Stereotypes, it is handled in
  UMLWidget::slotMenuSelection().

umbrello/menus/widgetbasepopupmenu.cpp
- Adjust function makeClassifierShowPopup to changed return type of
  UMLWidget::showStereotype().

umbrello/dialogs/pages/classoptionspage.{h,cpp}
- Change type of member m_showStereotypeCB to KComboBox*.
  Reason: It shall represent the values of Uml::ShowStereoType::Enum.
- New function createShowStereotypeCB(QGroupBox*) encapsulates creation
  of the KComboBox for m_showStereotype.
  For the moment this is a member method but it could be made "static"
  or be moved to Dialog_Utils.

CCBUG: 73847