Core/Utils: Migrate further to Utils::Id

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

Change-Id: I8c44590f7b988b3770ecdc177c40783e12353e66
(cherry picked from commit 430a33dcd9)
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/qmlprojectmanager/qmlproject.cpp

@@ -62,6 +62,7 @@
 using namespace Core;
 using namespace ProjectExplorer;
 using namespace QmlProjectManager::Internal;
+using namespace Utils;
 
 namespace {
 Q_LOGGING_CATEGORY(infoLogger, "QmlProjectManager.QmlBuildSystem", QtInfoMsg)