Move InfoBar to Utils

The only reason it was required to be in Core plugin, was its use of Id,
which now is available in Utils.

Change-Id: I66ce863c24924e6448d339b3422538a7fe167336
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/coreplugin/icore.h

@@ -42,10 +42,13 @@ class QStatusBar;
 class QWidget;
 QT_END_NAMESPACE
 
+namespace Utils {
+class InfoBar;
+}
+
 namespace Core {
 class Context;
 class IContext;
-class InfoBar;
 class IWizardFactory;
 class SettingsDatabase;
 
@@ -100,7 +103,7 @@ public:
 
     static QMainWindow *mainWindow();
     static QWidget *dialogParent();
-    static InfoBar *infoBar();
+    static Utils::InfoBar *infoBar();
 
     static void raiseWindow(QWidget *widget);