Enable Source link for debugging enhancements (#60)

- [Source
Link](https://learn.microsoft.com/en-us/dotnet/standard/library-guidance/sourcelink)
reference
> Source Link is a technology that enables source code debugging of .NET
assemblies from NuGet by developers. Source Link executes when creating
the NuGet package and embeds source control metadata inside assemblies
and the package. Developers who download the package and have Source
Link enabled in Visual Studio can step into its source code. Source Link
provides source control metadata to create a great debugging experience.
- See example from Newtonsoft.Json
https://github.com/JamesNK/Newtonsoft.Json/blob/master/Src/Newtonsoft.Json/Newtonsoft.Json.csproj
- Also producing [symbol packages
(.snupkg)](https://learn.microsoft.com/en-us/nuget/create-packages/symbol-packages-snupkg?source=recommendations)
to include debug symbols

Federation/ApolloGraphQL.HotChocolate.Federation.csproj

@@ -7,14 +7,18 @@
     <AssemblyName>ApolloGraphQL.HotChocolate.Federation</AssemblyName>
     <Description>Apollo Federation Subgraph support for HotChocolate.</Description>
     <PackageReadmeFile>README.md</PackageReadmeFile>
+    <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
   </PropertyGroup>
 
   <ItemGroup>
     <InternalsVisibleTo Include="ApolloGraphQL.HotChocolate.Federation.Tests" />
   </ItemGroup>
 
-  <ItemGroup> 
+  <ItemGroup>
     <PackageReference Include="HotChocolate" Version="13.6.1" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All"/>
   </ItemGroup>
 
   <ItemGroup>