引入 UISerializationRoot 和 Item

- 完成 MenuForm 和 SelectRoleForm 的迁移

Assets/GameMain/Scripts/Presentation/Main/Shop/DisplayItem.cs

@@ -23,16 +23,11 @@ namespace SepCore.UI
 
         public async UniTaskVoid OnInit(DisplayItemContext context, int index)
         {
-            if (context == null) return;
-
             _context = context;
             _index = index;
 
-            if (_iconArea != null)
-            {
-                var sprite = await SpriteLoader.LoadSpriteByKeyAsync(_context.IconAssetName);
-                _iconArea.OnInit(sprite, context.Rarity);
-            }
+            var sprite = await SpriteLoader.LoadSpriteByKeyAsync(_context.IconAssetName);
+            _iconArea.OnInit(sprite, _context.Rarity);
         }
 
         public void OnReset()
@@ -40,16 +35,12 @@ namespace SepCore.UI
             _context = null;
             _index = -1;
 
-            if (_iconArea != null)
-            {
-                _iconArea.OnReset();
-            }
+            _iconArea.OnReset();
         }
 
         public void OnItemInfoShow()
         {
             if (_index < 0) return;
-            if (_itemRect == null) return;
 
             Rect rect = _itemRect.rect;
             Vector3 targetPos = _itemRect.TransformPoint(new Vector3(