!1874 fix(#I4ASEJ): no trigger OnCellRender when set AutoGenerateColumn to true

* fix: 修复开启自动生成列后不触发 OnCellRender 回调问题

src/BootstrapBlazor/Components/Table/InternalTableColumn.cs

@@ -251,6 +251,7 @@ namespace BootstrapBlazor.Components
             if (source.Rows > 0) dest.Rows = source.Rows;
             if (source.ComponentType != null) dest.ComponentType = source.ComponentType;
             if (source.ComponentParameters != null) dest.ComponentParameters = source.ComponentParameters;
+            if (source.OnCellRender != null) dest.OnCellRender = source.OnCellRender;
         }
     }
 }

src/BootstrapBlazor/Components/Table/Table.razor

@@ -618,7 +618,7 @@ RenderFragment<TItem> RenderRow => item =>
                     }
                     else
                     {
-                        @if (string.IsNullOrEmpty(value))
+                        @if (value == null)
                         {
                             @GetValue(col, item)
                         }