Use simpler Plugin::initialize() when feasible

Change-Id: I567965d266f20526bda9f823e31a04b354d53fb1
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/cvs/cvsplugin.h

@@ -14,7 +14,7 @@ class CvsPlugin final : public ExtensionSystem::IPlugin
 
     ~CvsPlugin() final;
 
-    bool initialize(const QStringList &arguments, QString *errorMessage) final;
+    void initialize() final;
     void extensionsInitialized() final;
 
 #ifdef WITH_TESTS