Made cpp file suffixes take effect after restart.

In CppTools, keep cpp file settings in plugin and settings page
via shared pointer and apply to mime DB in
extensionsInitialized() (after CppEditor has loaded
and registered the mime types).

Task-number: 252299

src/plugins/cpptools/cpptoolsplugin.h

@@ -32,6 +32,7 @@
 
 #include <extensionsystem/iplugin.h>
 #include <projectexplorer/projectexplorer.h>
+#include <QtCore/QSharedPointer>
 
 QT_BEGIN_NAMESPACE
 class QFileInfo;
@@ -43,11 +44,12 @@ namespace Internal {
 
 class CppCodeCompletion;
 class CppModelManager;
+struct CppFileSettings;
 
 class CppToolsPlugin : public ExtensionSystem::IPlugin
 {
+    Q_DISABLE_COPY(CppToolsPlugin)
     Q_OBJECT
-
 public:
     static CppToolsPlugin *instance() { return m_instance; }
 
@@ -70,6 +72,7 @@ private:
     int m_context;
     CppModelManager *m_modelManager;
     CppCodeCompletion *m_completion;
+    QSharedPointer<CppFileSettings> m_fileSettings;
 
     static CppToolsPlugin *m_instance;
 };