Package Windows Forms analyzers

Provide a mechanism to import Windows Forms specific analyzers from
Windows Forms transport package, and and package those into
Microsoft.WindowsDesktop.App.Ref bundle, so that they are available in
Windows Forms app out of the box.

The analyzers are referenced via props and targets located in
`C:\Program Files\dotnet\sdk\6.0.<version>\Sdks\Microsoft.NET.Sdk.WindowsDesktop\targets\`,
which is facilitated by dotnet/wpf#4605.

This work relates to dotnet/designs#223, and acts
as a workaround until dotnet/designs#181 is
approved and implemented.

pkg/windowsdesktop/sfx/Directory.Build.targets

@@ -37,6 +37,8 @@
         and it was removed in .NET 5.
     -->
     <IgnoredReference Include="System.Runtime.InteropServices.WindowsRuntime" />
+
+    <IgnoredReference Include="Microsoft.CodeAnalysis" />
   </ItemGroup>
 
   <Target Name="ReturnProductVersion" Returns="$(Version)" />

pkg/windowsdesktop/sfx/Microsoft.WindowsDesktop.App.Ref.sfxproj

@@ -2,12 +2,15 @@
   <Sdk Name="Microsoft.DotNet.SharedFramework.Sdk" />
   <PropertyGroup>
     <PlatformPackageType>TargetingPack</PlatformPackageType>
-    <WindowsFormsClassificationProps>$(PkgMicrosoft_Private_Winforms)\FrameworkListFiles.props</WindowsFormsClassificationProps>
     <RuntimePackProjectPath>$(MSBuildThisFileDirectory)Microsoft.WindowsDesktop.App.Runtime.sfxproj</RuntimePackProjectPath>
     <ArchiveName>windowsdesktop-targeting-pack</ArchiveName>
     <InstallerName>windowsdesktop-targeting-pack</InstallerName>
     <InstallerRuntimeIdentifiers>win-x64;win-x86;win-arm64</InstallerRuntimeIdentifiers>
     <VSInsertionShortComponentName>WindowsDesktop.TargetingPack</VSInsertionShortComponentName>
+
+    <_WinFormsContentPath>$(PkgMicrosoft_Private_Winforms)\WindowsDesktop.App.Ref</_WinFormsContentPath>
+    <_WindowsFormsContentProps>$(_WinFormsContentPath)\System.Windows.Forms.Analyzers.props</_WindowsFormsContentProps>
+    <_WindowsFormsContentTargets>$(_WinFormsContentPath)\System.Windows.Forms.Analyzers.targets</_WindowsFormsContentTargets>
   </PropertyGroup>
 
   <!-- 
@@ -43,7 +46,7 @@
     Windows Forms specific references
     see: https://github.com/dotnet/winforms/pull/2707/commits/50a5258f7039dc81d99b1c3896a94c578387a3be
     -->
-  <Import Project="$(WindowsFormsClassificationProps)" Condition="Exists('$(WindowsFormsClassificationProps)')" />
+  <Import Project="$(_WindowsFormsContentProps)" Condition="Exists('$(_WindowsFormsContentProps)')" />
 
   <!-- WPF specific references -->
   <ItemGroup>
@@ -73,4 +76,8 @@
     <!-- We don't have a ref assembly for DirectWriteForwarder -->
     <IgnoredReference Include="DirectWriteForwarder" />
   </ItemGroup>
+
+  <!-- Import Windows Forms specific targets -->
+  <Import Project="$(_WindowsFormsContentTargets)" Condition="Exists('$(_WindowsFormsContentTargets)')" />
+
 </Project>