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_dialog.cpp

@@ -13,6 +13,7 @@
 #include "lts_dialog_button_box.h"
 #include "lts_base_layout_widget.h"
 #include "lts_date_time_edit.h"
+#include "ui_requirement.h"
 
 #include <QHBoxLayout>
 #include <QProgressBar>
@@ -164,7 +165,6 @@ LtsDialog::LtsDialog(QWidget *parent, ButtonCombination buttonCombination, bool
       if (l)
       {
         l->setContentsMargins(0,0,0,0);
-        l->setMargin(0);
       }
       else
       {