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_image_editor.cpp

@@ -40,7 +40,7 @@ void LtsImageEditor::setPixmap(const QPixmap &pixmap)
 }
 
 
-void LtsImageEditor::enterEvent(QEvent *)
+void LtsImageEditor::enterEvent(QEnterEvent *)
 {
   //qWarning() << "enter";
   m_isHovered = true;