QmlDesigner: Implement new control design

* Update creator theme files and related enum
* Remove unused ActionIndicator functionality
* Update all controls (Colors, Positions, Sizes)
* Add global hover state and cleanup all other states
* Add global hover functionality to ButtonRow
* Add missing states
* Add new MenuItemWithIcon
* Add checkers.png for StateDelegate preview background
* Update copyright headers
* Replace AnchorButtons spacing
* Make ADS title bar buttons and tab bar buttons themeable
* Fix replace CSS colors to allow specifing alpha
* Fix replace CSS overwritting consecutive variables
* Make navigator icons and other elements themeable
* Make connection view themeable
* Make item library themeable
* Fix item library import path
* Update all HelperWidgets
* Fix GradientDialogPopup

Task-number: QDS-3768
Change-Id: I28a5fed178c95d098db052b8c2eabaa083d37b81
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/libs/advanceddockingsystem/dockwidgettab.h

@@ -38,6 +38,7 @@
 #include "ads_globals.h"
 
 #include <QFrame>
+#include <QToolButton>
 
 namespace ADS {
 
@@ -45,6 +46,28 @@ class DockWidget;
 class DockAreaWidget;
 class DockWidgetTabPrivate;
 
+using TabButtonType = QToolButton;
+
+class TabButton : public TabButtonType
+{
+    Q_OBJECT
+
+public:
+    using Super = TabButtonType;
+    TabButton(QWidget *parent = nullptr);
+
+    void setActive(bool value);
+    void setFocus(bool value);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+
+private:
+    bool m_active;
+    bool m_focus;
+};
+
+
 /**
  * A dock widget tab that shows a title and an icon.
  * The dock widget tab is shown in the dock area title bar to switch between