Add legacy feeds

Author: Evangelink

NuGet.config

@@ -19,6 +19,8 @@
     <add key="dotnet-tools" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json" />
     <add key="dotnet-public" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json" />
     <add key="vs-impl" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vs-impl/nuget/v3/index.json" />
+    <add key="vssdk-archived" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vssdk-archived/nuget/v3/index.json" />
+    <add key="vs-impl-archived" value="https://pkgs.dev.azure.com/azure-public/vside/_packaging/vs-impl-archived/nuget/v3/index.json" />
   </packageSources>
   <fallbackPackageFolders>
     <clear />