feat: 增加图标赋值逻辑

Author: ArgoZhang

src/BootstrapBlazor/Components/Dropdown/Dropdown.razor.cs

@@ -242,6 +242,11 @@ protected override void OnParametersSet()
 
         FixedButtonText ??= SelectedItem?.Text;
         LoadingIcon ??= IconTheme.GetIconByKey(ComponentIcons.ButtonLoadingIcon);
+
+        if (_isAsyncLoading == false)
+        {
+            _buttonIcon = Icon;
+        }
     }
 
     private IEnumerable<SelectedItem> GetItems() => (IsFixedButtonText && !ShowFixedButtonTextInDropdown)