Run CsWin32 generator as a build task and drop the IL2050 suppression

Bump CsWin32 to 0.3.298 and set CsWin32RunAsBuildTask=true centrally so the generator runs as an MSBuild build task. This improves IntelliSense performance and emits trim-safe/AOT-safe interop code, which makes the previous IL2050 suppression in UnitTest unnecessary (CA1420 is kept, as the COM 'object' parameter of CoRegisterClassObject still requires runtime marshalling). Also simplify the CsWin32 PackageReference in UnitTest and OOPExe to PrivateAssets=all.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Sergio0694

src/Directory.Build.props

@@ -119,6 +119,13 @@
       files aren't included. Once that issue is fixed, this should be restricted to published projects only.
     -->
     <GenerateDocumentationFile Condition="'$(IsPublicProject)' == 'true'">true</GenerateDocumentationFile>
+
+    <!--
+      Run the CsWin32 source generator as an MSBuild build task instead of an in-process Roslyn source
+      generator. This improves IntelliSense performance and lets CsWin32 generate trim-safe and AOT-safe
+      interop code. It's a no-op for projects that don't reference CsWin32.
+    -->
+    <CsWin32RunAsBuildTask>true</CsWin32RunAsBuildTask>
   </PropertyGroup>
 
   <!-- Set overrides to point to folder where they are built in solution -->

src/Directory.Packages.props

@@ -27,7 +27,7 @@
     <PackageVersion Include="Microsoft.VCRTForwarders.140" Version="1.1.0" />
     <PackageVersion Include="Microsoft.Web.WebView2" Version="1.0.3179.45" />
     <PackageVersion Include="Microsoft.Win32.Registry" Version="5.0.0" />
-    <PackageVersion Include="Microsoft.Windows.CsWin32" Version="0.1.635-beta" />
+    <PackageVersion Include="Microsoft.Windows.CsWin32" Version="0.3.298" />
     <PackageVersion Include="Microsoft.Windows.CsWinRT" Version="2.2.0" />
     <PackageVersion Include="Microsoft.Windows.SDK.BuildTools" Version="[10.0.22000.194]" />
     <PackageVersion Include="Microsoft.Windows.SDK.Contracts" Version="10.0.18362.2005" />

src/Tests/OOPExe/OOPExe.csproj

@@ -15,10 +15,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Windows.CsWin32">
-      <PrivateAssets>all</PrivateAssets>
-      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-    </PackageReference>
+    <PackageReference Include="Microsoft.Windows.CsWin32" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>

src/Tests/UnitTest/UnitTest.csproj

@@ -29,12 +29,12 @@
     <NoWarn>$(NoWarn);CA1416</NoWarn>
 
     <!--
-      The CsWin32 source generator emits a 'CoRegisterClassObject' P/Invoke (in 'Ole32') that uses COM
-      marshalling, which trips 'IL2050' (COM interop correctness under trimming) and 'CA1420' (requires
-      runtime marshalling, which is disabled repo-wide). This is generated code we don't control, so
-      suppress both here.
+      The CsWin32-generated 'CoRegisterClassObject' P/Invoke (in 'Ole32') takes a COM 'object' parameter
+      whose marshalling requires runtime marshalling, which is disabled repo-wide, so it trips 'CA1420'.
+      This is generated code we don't control, so suppress it here. (With 'CsWin32RunAsBuildTask=true' the
+      generator now emits trim-safe/AOT-safe code, so the previous 'IL2050' suppression is no longer needed.)
     -->
-    <NoWarn>$(NoWarn);IL2050;CA1420</NoWarn>
+    <NoWarn>$(NoWarn);CA1420</NoWarn>
     <SelfContained>true</SelfContained>
     <CsWinRTEnabled>false</CsWinRTEnabled>
     <OutputType>exe</OutputType>
@@ -72,10 +72,7 @@
     <!--<ProjectReference Include="..\OOPExe\OOPExe.csproj" />-->
 
     <PackageReference Include="Microsoft.VCRTForwarders.140" />
-    <PackageReference Include="Microsoft.Windows.CsWin32">
-        <PrivateAssets>all</PrivateAssets>
-        <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-    </PackageReference>
+    <PackageReference Include="Microsoft.Windows.CsWin32" PrivateAssets="all" />
     <PackageReference Include="Newtonsoft.Json" />
     <ProjectReference Include="..\..\Authoring\WinRT.SourceGenerator2\WinRT.SourceGenerator2.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" SetPlatform="Platform=AnyCPU" />     
   </ItemGroup>