ProjectExplorer: Promote CppProjectUpdaterInterface

... to ProjectExplorer::ProjectUpdaterInterface and generalize it
regarding language, but create a convience function for the C++
case, as that's the only user right now.

Also add the self-registering factory boilerplate and adapt all
buildsystems.

Change-Id: If928512609d41c25fad2aa58633c8bffabc4c48f
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/autotoolsprojectmanager/autotoolsbuildsystem.h

@@ -7,7 +7,7 @@
 
 #include <memory>
 
-namespace CppEditor { class CppProjectUpdater; }
+namespace ProjectExplorer { class ProjectUpdater; }
 
 namespace AutotoolsProjectManager::Internal {
 
@@ -42,7 +42,7 @@ private:
     /// Responsible for parsing the makefiles asynchronously in a thread
     std::unique_ptr<MakefileParserThread> m_makefileParserThread;
 
-    CppEditor::CppProjectUpdater *m_cppCodeModelUpdater = nullptr;
+    ProjectExplorer::ProjectUpdater *m_cppCodeModelUpdater = nullptr;
 };
 
 } // AutotoolsProjectManager::Internal