Skip checking for packages.config in SDK-style projects

Author: Sergio0694

src/CommunityToolkit.Mvvm/CommunityToolkit.Mvvm.targets

@@ -102,15 +102,19 @@
     </ItemGroup>
   </Target>
 
-  <!-- Remove the analyzer if packages.config is used -->
+  <!--
+    Inform the user if packages.config is used (as the analyzers and the source generators
+    won't work at all). Since packages.config can only be used with legacy-style projects,
+    the entire package can be skipped if an SDK-style project is used.
+  -->
   <Target Name="MVVMToolkitWarnForPackagesConfigUse"
           AfterTargets="ResolvePackageDependenciesForBuild;ResolveNuGetPackageAssets"
-          DependsOnTargets="MVVMToolkitGatherAnalyzers">
+          Condition="'$(UsingMicrosoftNetSDK)' != 'true'">
 
     <!--
       Check whether packages are being restored via packages.config, by reading the associated MSBuild property.
       This happens when either the project style is using packages.config, or when explicitly requested.
-      See https://learn.microsoft.com/en-us/nuget/reference/msbuild-targets#restoring-packagereference-and-packagesconfig-projects-with-msbuild.
+      See https://learn.microsoft.com/nuget/reference/msbuild-targets#restoring-packagereference-and-packagesconfig-projects-with-msbuild.
     -->
     <PropertyGroup>
       <MVVMToolkitIsTargetProjectUsingPackagesConfig Condition ="'$(RestorePackagesConfig)' == 'true' OR '$(RestoreProjectStyle)' == 'PackagesConfig'">true</MVVMToolkitIsTargetProjectUsingPackagesConfig>
@@ -120,6 +124,8 @@
       If no packages.config properties are set, also try to manually find the packages.config file.
       This will be in the @(None) elements, if present. Doing so makes sure this works in builds as
       well, since the implicit targets populating the properties above only run when restoring.
+      Since the packages.config file will always be in the root of the project, if present, we will
+      match with the full item spec (see https://learn.microsoft.com/nuget/reference/packages-config).
     -->
     <FindInList ItemSpecToFind="packages.config"
                 List="@(None)"