CMakeProjectManager: settings page code cosmetics

Change-Id: I657fa72d5b625877dc1deec229f6f5c7c16358fd
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

src/plugins/cmakeprojectmanager/cmakesettingspage.h

@@ -5,8 +5,7 @@
 
 #include <coreplugin/dialogs/ioptionspage.h>
 
-namespace CMakeProjectManager {
-namespace Internal {
+namespace CMakeProjectManager::Internal {
 
 class CMakeSettingsPage final : public Core::IOptionsPage
 {
@@ -14,5 +13,4 @@ public:
     CMakeSettingsPage();
 };
 
-} // namespace Internal
-} // namespace CMakeProjectManager
+} // CMakeProjectManager::Internal