Updated the default namespace for new components (#394)

* Updated default root namespace and PackageId

* Doc fix

* Renamed template csproj

* Move PackageId prefix to property in Directory.Build.props

* Moved code / docs to new default namespace

* Use xmlns:controls instead of xmlns:labs

* Use xmlns:controls instead of xmlns:labs

* Fixed xaml styling

* Removed default component namespace from global usings

* Unify default package ID

* Fixed missing using directive

* Fixed missing using directive

Author: Arlodotexe

GlobalUsings_WinUI.cs

@@ -7,8 +7,6 @@
 
 global using System.Runtime.InteropServices.WindowsRuntime;
 
-global using CommunityToolkit.Labs.WinUI;
-
 global using Windows.Foundation;
 global using Windows.Foundation.Collections;
 

ToolkitComponent.SourceProject.props

@@ -10,7 +10,7 @@
   <Import Project="$(RepositoryDirectory)common\MultiTarget\MultiTarget.props" />
 
   <PropertyGroup>
-    <PackageId Condition="'$(PackageId)' == ''">CommunityToolkit.Labs.$(PackageIdVariant).$(ToolkitComponentName)</PackageId>
+    <PackageId Condition="'$(PackageId)' == ''">$(PackageIdPrefix).$(PackageIdVariant).$(ToolkitComponentName)</PackageId>
   </PropertyGroup>
 
   <!-- XAML Pages are automatically included, and don't need to be specified here. -->