Core/Utils: Migrate further to Utils::Id

The coreplugin/id.h header is kept for downstream for now.

Change-Id: I8c44590f7b988b3770ecdc177c40783e12353e66
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/coreplugin/designmode.cpp

@@ -35,11 +35,10 @@
 
 #include <extensionsystem/pluginmanager.h>
 
-#include <QPointer>
-#include <QStringList>
 #include <QDebug>
-
+#include <QPointer>
 #include <QStackedWidget>
+#include <QStringList>
 
 namespace Core {
 
@@ -201,7 +200,7 @@ void DesignMode::updateActions()
     emit actionsUpdated(d->m_currentEditor.data());
 }
 
-void DesignMode::updateContext(Id newMode, Id oldMode)
+void DesignMode::updateContext(Utils::Id newMode, Utils::Id oldMode)
 {
     if (newMode == id())
         ICore::addAdditionalContext(d->m_activeContext);