refactor: 增加样式支持

Author: ArgoZhang

src/components/BootstrapBlazor.CherryMarkdown/Components/CherryMarkdown/CherryMarkdown.razor

@@ -6,4 +6,4 @@
 {
     <BootstrapLabel required="@Required" for="@Id" ShowLabelTooltip="ShowLabelTooltip" Value="@DisplayText" />
 }
-<div @attributes="@AdditionalAttributes" id="@Id"></div>
+<div @attributes="@AdditionalAttributes" id="@Id" class="@ClassString"></div>

src/components/BootstrapBlazor.CherryMarkdown/Components/CherryMarkdown/CherryMarkdown.razor.cs

@@ -62,6 +62,11 @@ public partial class CherryMarkdown
     [Parameter]
     public string? Language { get; set; }
 
+    private string? ClassString => CssBuilder.Default("bb-cherry-markdown")
+        .AddClass(CssClass)
+        .AddClass(ValidCss)
+        .Build();
+
     /// <summary>
     /// <inheritdoc/>
     /// </summary>