Added Disabled flag to Achievement Manager

The Disabled state sits between Game Closed and completely Shutdown - stronger than the former, as it refuses to let a game be opened again until AchievementManager is restored (which only happens upon a fresh core boot) but it isn't completely shut down and will still allow the player to be logged in and access the achievement settings and their (global) achievement header.

Source/Core/Core/ConfigManager.cpp

@@ -30,6 +30,7 @@
 #include "Common/StringUtil.h"
 #include "Common/Version.h"
 
+#include "Core/AchievementManager.h"
 #include "Core/Boot/Boot.h"
 #include "Core/CommonTitles.h"
 #include "Core/Config/DefaultLocale.h"
@@ -168,6 +169,10 @@ void SConfig::SetRunningGameMetadata(const std::string& game_id, const std::stri
   if (!was_changed)
     return;
 
+#ifdef USE_RETRO_ACHIEVEMENTS
+  AchievementManager::GetInstance()->SetDisabled(true);
+#endif  // USE_RETRO_ACHIEVEMENTS
+
   if (game_id == "00000000")
   {
     m_title_name.clear();