refactor: 增加 Tab 默认首页

src/blazor/client/BootstrapClient.Shared/Pages/Index.razor

@@ -1,5 +1,6 @@
 @page "/"
 @page "/Home/Index"
+@attribute [TabItemOption(Text = "首页", Icon = "fa fa-fa")]
 
 <h1>Hello, world!</h1>
 

src/blazor/client/BootstrapClient.Shared/Shared/MainLayout.razor

@@ -3,6 +3,7 @@
 <Layout SideWidth="0" IsPage="true" ShowGotoTop="true" ShowCollapseBar="true"
         IsFullSide="@IsFullSide" IsFixedHeader="@IsFixedHeader" IsFixedFooter="@IsFixedFooter" ShowFooter="@ShowFooter"
         Menus="@MenuItems" UseTabSet="@UseTabSet" TabItemTextDictionary="@TabItemTextDictionary" 
+        TabDefaultUrl="/Home/Index"
         AdditionalAssemblies="new[] { GetType().Assembly }" OnAuthorizing="@OnAuthorizing" class="@Theme">
     <Header>
         <span class="ml-3 flex-sm-fill d-none d-sm-block">Bootstrap of Blazor</span>

src/blazor/client/BootstrapClient.Shared/Shared/Widget.razor

@@ -1,4 +1,4 @@
-<DropdownWidget class="text-right flex-fill px-3">
+<DropdownWidget class="text-right px-3">
     <DropdownWidgetItem Icon="fa fa-envelope-o" BadgeNumber="4">
         <HeaderTemplate>
             <span>您有 4 个未读消息</span>