ProjectExplorer: Add a common template for project settings

- Added base widget class for common options among project settings tabs
- Added usage new template class to all pages used in project settings

ToDo
- Make CodeStyle tab standardized

Change-Id: I8f70413b6ee764c5e43fbeae104b9389237c582f
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangtools/clangtoolsplugin.cpp

@@ -126,7 +126,8 @@ bool ClangToolsPlugin::initialize(const QStringList &arguments, QString *errorSt
     panelFactory->setPriority(100);
     panelFactory->setId(Constants::PROJECT_PANEL_ID);
     panelFactory->setDisplayName(tr("Clang Tools"));
-    panelFactory->setCreateWidgetFunction([](Project *project) { return new ProjectSettingsWidget(project); });
+    panelFactory->setCreateWidgetFunction(
+        [](Project *project) { return new ClangToolsProjectSettingsWidget(project); });
     ProjectPanelFactory::registerFactory(panelFactory);
 
     connect(Core::EditorManager::instance(),