Enable interactive optional tools authentication

eng/Tools.props

@@ -60,13 +60,25 @@
   </ItemGroup>
 
   <!--
-    Temporarily opt-in as dotnet restore interactive doesn't seem to work.
-    https://github.com/NuGet/Home/issues/7812. Use nuget restore meanwhile.
+    Restore internals tools if OptionalToolSource environment variable is set or
+    /p:RestoreInternalTools=true is passed in.
   -->
   <Target Name="InitOptionalTools"
-          Condition="'$(RestoreInternalTools)' == 'true'"
+          Condition="'$(OptionalToolSource)' != '' or '$(RestoreInternalTools)' == 'true'"
           AfterTargets="Restore">
 
+    <PropertyGroup>
+      <CredentialsProviderScriptUrl Condition="'$(OS)' == 'Windows_NT'">https://raw.githubusercontent.com/Microsoft/artifacts-credprovider/master/helpers/installcredprovider.ps1</CredentialsProviderScriptUrl>
+      <CredentialsProviderScriptUrl Condition="'$(OS)' != 'Windows_NT'">https://raw.githubusercontent.com/Microsoft/artifacts-credprovider/master/helpers/installcredprovider.sh</CredentialsProviderScriptUrl>
+    </PropertyGroup>
+
+    <DownloadFile SourceUrl="$(CredentialsProviderScriptUrl)" DestinationFolder="$(ArtifactsDir)">
+      <Output TaskParameter="DownloadedFile" ItemName="CredentialsProviderScriptPath" />
+    </DownloadFile>
+
+    <Exec Condition="'$(OS)' == 'Windows_NT'" Command="powershell -ExecutionPolicy ByPass -NoProfile -File &quot;%(CredentialsProviderScriptPath.Identity)&quot;" />
+    <Exec Condition="'$(OS)' != 'Windows_NT'" Command="chmod +x &quot;%(CredentialsProviderScriptPath.Identity)&quot; %26%26 &quot;%(CredentialsProviderScriptPath.Identity)&quot;" />
+
     <PropertyGroup>
       <OptionalToolDir>$([MSBuild]::NormalizeDirectory('$(RepositoryEngineeringDir)', 'common', 'internal'))</OptionalToolDir>
       <OptionalToolProjectPath>$(OptionalToolDir)Tools.csproj</OptionalToolProjectPath>