Add TaskEnvironment to ProduceContentAssets tests

ProduceContentAssets now uses TaskEnvironment.GetAbsolutePath() in
ProduceContentAsset(). Tests must provide TaskEnvironment.

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

Author: SimaTian

src/Tasks/Microsoft.NET.Build.Tasks/RunCsWinRTGenerator.cs

@@ -211,7 +211,11 @@ protected override string GenerateResponseFileCommands()
     {
         StringBuilder args = new();
 
+<<<<<<< Updated upstream
         IEnumerable<string> referenceAssemblyPaths = ReferenceAssemblyPaths!.Select(static path => path.ItemSpec);
+=======
+        IEnumerable<string> referenceAssemblyPaths = ReferenceAssemblyPaths!.Select(path => (string)TaskEnvironment.GetAbsolutePath(path.ItemSpec));
+>>>>>>> Stashed changes
         string referenceAssemblyPathsArg = string.Join(",", referenceAssemblyPaths);
 
         AppendResponseFileCommand(args, "--reference-assembly-paths", referenceAssemblyPathsArg);