CheatsManager: Create ARCodeWidget and GeckoCodeWidget only once.

Create ARCodeWidget and GeckoCodeWidget once on startup rather than
every time a game is launched or shutdown.

In addition to losing focus on the tab (since the previous widget and
tab no longer existed), the behavior prior to this commit could cause a
crash if the user initiated a game shutdown and then opened a code edit
window since the AR/GeckoCodeWidget would get deleted in the meantime.

Source/Core/DolphinQt/CheatsManager.h

@@ -58,7 +58,7 @@ private:
   void OnNewSessionCreated(const Cheats::CheatSearchSessionBase& session);
   void OnTabCloseRequested(int index);
 
-  void RefreshCodeTabs(Core::State state, bool force);
+  void RefreshCodeTabs(Core::State state);
   void UpdateAllCheatSearchWidgetCurrentValues();
 
   std::string m_game_id;