Temporary introduce rc1 workaround to arcade tools restore until ther…

…e's a fix

eng/common/internal/Tools.csproj

@@ -6,6 +6,31 @@
     <AutomaticallyUseReferenceAssemblyPackages>false</AutomaticallyUseReferenceAssemblyPackages>
     <BuildWithNetFrameworkHostedCompiler>false</BuildWithNetFrameworkHostedCompiler>
   </PropertyGroup>
+   <!-- BEGIN workaround for https://github.com/dotnet/sdk/issues/43339; remove after updated to VS 17.12, future 17.11 patch or when arcade ships the the same workaround -->
+  <Target Name="WorkaroundDotnetSdk43339" BeforeTargets="ResolvePackageAssets" Condition=" '$(MSBuildRuntimeType)' == 'Full' and $([MSBuild]::VersionLessThan($(MSBuildVersion), 17.12.0))">
+    <PrimeSystemTextJson804 />
+  </Target>
+  <UsingTask
+    TaskName="PrimeSystemTextJson804"
+    TaskFactory="RoslynCodeTaskFactory"
+    AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll" >
+    <Task>
+      <Code Type="Fragment" Language="cs">
+<![CDATA[
+try
+{
+    System.Reflection.Assembly.LoadFrom(@"$(MicrosoftNETBuildTasksDirectoryRoot)\..\..\..\DotnetTools\dotnet-format\BuildHost-net472\System.Text.Json.dll");
+}
+catch
+{
+    // Best effort: if something moves in the SDK don't break the build.
+}
+]]>
+      </Code>
+    </Task>
+  </UsingTask>
+  <!-- END workaround for https://github.com/dotnet/sdk/issues/43339 -->
+
   <ItemGroup>
     <!-- Clear references, the SDK may add some depending on UsuingToolXxx settings, but we only want to restore the following -->
     <PackageReference Remove="@(PackageReference)"/>