Import the new Microsoft.Common.Test.targets target for multi-tfm (#9583)

Co-authored-by: Marco Rossignoli <[email protected]>

Author: MarcoRossignoli

src/Tasks/Microsoft.Common.CrossTargeting.targets

@@ -248,4 +248,9 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
   <Import Project="$(DirectoryBuildTargetsPath)" Condition="'$(ImportDirectoryBuildTargets)' == 'true' and exists('$(DirectoryBuildTargetsPath)')"/>
 
+  <PropertyGroup>
+    <UseMSBuildTestInfrastructure Condition="'$(UseMSBuildTestInfrastructure)' == ''">false</UseMSBuildTestInfrastructure>
+  </PropertyGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.Common.Test.targets" Condition="'$(UseMSBuildTestInfrastructure)' == 'true'"/>
+
 </Project>