Red code legacy MemoryManager, StreamEngine, ResourceManager, ImageHandler, AsyncPakManager, and more (#758)

Remove from CryCommon and CrySystem:
- MemoryManager and all related classes/files
- StreamEngine, ResourceManager, ImageHandler, and AsyncPakManager
- Various other related interfaces/files/classes etc. that are all now unused

Code/CryEngine/CrySystem/LevelSystem/LevelSystem.cpp

@@ -17,7 +17,6 @@
 #include "LevelSystem.h"
 #include <IAudioSystem.h>
 #include "IMovieSystem.h"
-#include <IResourceManager.h>
 #include <ILocalizationManager.h>
 #include "CryPath.h"
 #include <Pak/CryPakUtils.h>
@@ -778,9 +777,6 @@ void CLevelSystem::PrepareNextLevel(const char* levelName)
         // switched to level heap, so now imm start the loading screen (renderer will be reinitialized in the levelheap)
         gEnv->pSystem->GetISystemEventDispatcher()->OnSystemEvent(ESYSTEM_EVENT_LEVEL_LOAD_START_LOADINGSCREEN, 0, 0);
         gEnv->pSystem->SetSystemGlobalState(ESYSTEM_GLOBAL_STATE_LEVEL_LOAD_START_PREPARE);
-
-        // Inform resource manager about loading of the new level.
-        GetISystem()->GetIResourceManager()->PrepareLevel(pLevelInfo->GetPath(), pLevelInfo->GetName());
     }
 
     for (AZStd::vector<ILevelSystemListener*>::const_iterator it = m_listeners.begin(); it != m_listeners.end(); ++it)
@@ -987,8 +983,6 @@ void CLevelSystem::UnloadLevel()
 
     m_lastLevelName.clear();
 
-    GetISystem()->GetIResourceManager()->UnloadLevel();
-
     SAFE_RELEASE(m_pCurrentLevel);
     
     // Force Lua garbage collection (may no longer be needed now the legacy renderer has been removed).