Add dnx to the linux packaging layout (#50838)

Author: jkoritzinsky

src/Layout/pkg/dotnet-sdk.proj

@@ -48,6 +48,10 @@
     <PackageReference Include="Microsoft.DotNet.Build.Tasks.Installers" />
   </ItemGroup>
 
+  <ItemGroup>
+    <LinuxPackageSymlink Include="/usr/bin/dnx" LinkTarget="../share/dotnet/dnx" />
+  </ItemGroup>
+
   <Import Project="$(RepoRoot)src\Tasks\sdk-tasks\sdk-tasks.InTree.targets" />
 
   <PropertyGroup>
@@ -61,6 +65,7 @@
       <CLISdkFiles Include="$(RedistInstallerLayoutPath)sdk/**/*" />
       <TemplatesFiles Include="$(RedistInstallerLayoutPath)templates/**/*" />
       <ManifestFiles Include="$(RedistInstallerLayoutPath)sdk-manifests/**/*" />
+      <DnxShimSource Include="$(RedistInstallerLayoutPath)dnx*" />
     </ItemGroup>
 
     <!-- Create layout: Binaries -->
@@ -89,6 +94,9 @@
       OverwriteReadOnlyFiles="True"
       SkipUnchangedFiles="False"
       UseHardlinksIfPossible="False" />
+
+    <!-- Create layout: DNX shim -->
+    <Copy SourceFiles="@(DnxShimSource)" DestinationFolder="$(OutputPath)" />
   </Target>
 
   <Target Name="SetCustomPackagingProperties" AfterTargets="_GetInstallerProperties">