umbrello/petaltree2uml.cpp function umbrellify completion of statemachine statediagrams conversion:

- Local viewTagToWidget is a QMap<QString, UMLWidget*> mapping a view
  object's tag (number preceded by "@") to the Umbrello widget created.
- In case (dt != Uml::DiagramType::Undefined) :
  - Local qreal maxY is initialized to 0.0 and is set to the largest Y
    (plus height) coordinate encountered during conversion of widgets.
  - Move declaration of locals `width` and `height` to inside for-loop.
  - Local UMLWidgetList swimlanes is an auxiliary list for adjusting the
    final height of swimlanes to contain all widgets.
  - Convert TransView to AssociationWidget with type State or Activity
    depending on the diagram type.
  - On converting Swimlane call swimlanes.append(w).
  - On converting StateView initialize `width` and `height` from
    w->width() and w->height(), respectively.
  - Convert DecisionView to ActivityWidget with ActivityType `Branch`.
  - Convert SynchronizationView to ForkJoinWidget with Qt::Orientation
    according to Rose attribute sync_is_horizontal.
  - Fill viewTagToWidget with attr->viewTag() as key and `w` (pointer
    to UMLWidget) as value.
  - After the conversion loop iterate over `swimlanes` for adjusting
    each swimlane's height to maxY.

CCBUG: 81364