Removed the old Memory Arena and converted all to the new one

JulietApp/main.cpp

@@ -198,8 +198,8 @@ void JulietApplication::Init()
         if ((Running = GameCode.IsValid))
         {
             GameInitParams params;
-            params.GameArena    = GetGameArena();
-            params.ScratchArena = GetScratchArena();
+            params.GameArena    = ArenaAllocate({} JULIET_DEBUG_ONLY(, "Game Arena"));
+            params.ScratchArena = ArenaAllocate({} JULIET_DEBUG_ONLY(, "Scratch Arena"));
             Game.Init(&params);
         }
     }