Use MainCallback wherever posible (#2184)

include/item_menu.h

@@ -2,6 +2,7 @@
 #define GUARD_ITEM_MENU_H
 
 #include "item.h"
+#include "main.h"
 #include "menu_helpers.h"
 
 enum {
@@ -47,7 +48,7 @@ enum {
 
 struct BagPosition
 {
-    void (*exitCallback)(void);
+    MainCallback exitCallback;
     u8 location;
     u8 pocket;
     u16 pocketSwitchArrowPos;
@@ -59,7 +60,7 @@ extern struct BagPosition gBagPosition;
 
 struct BagMenu
 {
-    void (*newScreenCallback)(void);
+    MainCallback newScreenCallback;
     u8 tilemapBuffer[BG_SCREEN_SIZE];
     u8 spriteIds[ITEMMENUSPRITE_COUNT];
     u8 windowIds[ITEMWIN_COUNT];
@@ -96,10 +97,10 @@ void CB2_BagMenuFromStartMenu(void);
 u8 GetItemListPosition(u8 pocketId);
 bool8 UseRegisteredKeyItemOnField(void);
 void CB2_GoToSellMenu(void);
-void GoToBagMenu(u8 location, u8 pocket, void ( *exitCallback)());
+void GoToBagMenu(u8 location, u8 pocket, MainCallback exitCallback);
 void DoWallyTutorialBagMenu(void);
 void ResetBagScrollPositions(void);
-void ChooseBerryForMachine(void (*exitCallback)(void));
+void ChooseBerryForMachine(MainCallback exitCallback);
 void CB2_ChooseBerry(void);
 void Task_FadeAndCloseBagMenu(u8 taskId);
 void BagMenu_YesNo(u8 taskId, u8 windowType, const struct YesNoFuncTable *funcTable);