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/ios/iosbuildstep.cpp

@@ -71,7 +71,7 @@ class IosBuildStep final : public AbstractProcessStep
     Q_DECLARE_TR_FUNCTIONS(Ios::Internal::IosBuildStep)
 
 public:
-    IosBuildStep(BuildStepList *parent, Core::Id id);
+    IosBuildStep(BuildStepList *parent, Utils::Id id);
 
     BuildStepConfigWidget *createConfigWidget() final;
     void setBaseArguments(const QStringList &args);