Fix .targets again, add basic test

Author: Sergio0694

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.Tests/CommunityToolkit.DependencyPropertyGenerator.Tests.csproj

@@ -40,4 +40,7 @@
       Link="EmbeddedResources\GeneratedDependencyPropertyAttribute.cs"
       LogicalName="GeneratedDependencyPropertyAttribute.g.cs" />
   </ItemGroup>
+
+  <!-- Import the .targets from the package, just as a sanity check to verify they're not invalid -->
+  <Import Project="..\src\CommunityToolkit.WinUI.DependencyPropertyGenerator.targets" />
 </Project>

components/DependencyPropertyGenerator/src/CommunityToolkit.WinUI.DependencyPropertyGenerator.targets

@@ -50,8 +50,8 @@
   <!-- Check the Roslyn version and warn if it's not high enough (we don't need to remove the analyzers, as they're leveraging multi-targeting) -->
   <Target Name="CommunityToolkitGeneratedDependencyPropertyWarnForRoslynVersionNotHighEnough"
           Condition="'$(CSharpCoreTargetsPath)' != ''"
-          AfterTargets="ResolvePackageDependenciesForBuild;ResolveNuGetPackageAssets"
-          DependsOnTargets="CommunityToolkitGeneratedDependencyPropertyGatherAnalyzers">
+          DependsOnTargets="ResolveAssemblyReferences"
+          BeforeTargets="CoreCompile">
 
     <!--
       Use the CSharpCoreTargetsPath property to find the version of the compiler we are using. This is the same mechanism