LtsWidgets: Qt6 API fixes complete

- QComboBox::activated signal: QString→int parameter (lts_text_editor)
- qAsConst→std::as_const (5 files)
- localPos()→position() (lts_height_plot_widget)
- setMargin→setContentsMargins (tests/window.cpp)
- CMAKE_AUTOUIC OFF + include in header for MOC
- enterEvent(QEnterEvent*) signature fixes
- QRegExp→QRegularExpression replacements

All LtsWidgets module files now Qt6-compatible.

qt6-after/qt6-migrated-legatus/Lts/Common/LtsWidgets/lts_abstract_sequence_widget.cpp

@@ -8,6 +8,8 @@
   */
 #include "lts_abstract_sequence_widget.h"
 
+#include <QRegularExpression>
+
 #include <QToolButton>
 
 namespace LtsWidgets
@@ -119,7 +121,7 @@ void LtsAbstractSequenceWidget::deleteMemberWidget(QObject *member)
 
       QString childName = child->objectName();
       QString newId = QString::number(i + 1);
-      child->setObjectName(childName.replace(QRegExp(QLatin1String(".([0-9]*)")), newId));
+      child->setObjectName(childName.replace(QRegularExpression(QLatin1String("\\.([0-9]*)")), newId));
     }
   }
 }