Add PackageReferences to custom-generated ref assemblies

Author: wtgodbe

eng/targets/ReferenceAssembly.targets

@@ -105,6 +105,9 @@
       <_ReferenceAssemblyItems
           Include="@(FilteredOriginalReferences->'&lt;Reference Include=&quot;%(Identity)&quot; /&gt;')"
           Condition=" '@(FilteredOriginalReferences)' != '' " />
+      <_ReferenceAssemblyItems
+          Include="@(_ExplicitPackageReference->'&lt;PackageReference Include=&quot;%(Identity)&quot; Version=&quot;%(Version)&quot; /&gt;')"
+          Condition=" '@(_ExplicitPackageReference)' != '' " />
       <!-- Some src/ projects use Arcade SDK feature to generate InternalsVisibleTo attributes. -->
       <_ReferenceAssemblyItems
           Include="@(InternalsVisibleTo->'&lt;InternalsVisibleTo Include=&quot;%(Identity)&quot; Key=&quot;%(Key)&quot; /&gt;')"