ProjectExplorer: Pass Id to BuildStep constructor

Allows to use constants in fewer places, similar to what e.g.
RunConfiguration does.

Change-Id: I9d049128206c4acf0ce14b06b66d6c090a7c5242
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/qbsprojectmanager/qbsbuildstep.cpp

@@ -137,8 +137,8 @@ private:
 // QbsBuildStep:
 // --------------------------------------------------------------------
 
-QbsBuildStep::QbsBuildStep(ProjectExplorer::BuildStepList *bsl) :
-    ProjectExplorer::BuildStep(bsl, Constants::QBS_BUILDSTEP_ID)
+QbsBuildStep::QbsBuildStep(BuildStepList *bsl, Core::Id id) :
+    BuildStep(bsl, id)
 {
     setDisplayName(tr("Qbs Build"));
     setQbsConfiguration(QVariantMap());