Add a boolean property named ProducesNetCoreAssets in Publishing.props for repos that produce .NET shipping packages (packages that we ship with the release infra)
Based on this property we will select which packages to ship as part of .NET on release day.

Add the metadata to assets in prepare-artifacts.proj since runtime doesn't use arcades default publishing

This is a infrastructure only change. It will add extra metadata to the MergedManifest.xml produced during CI build.

Details are in Set ProducesNetCoreAssets property for repos that produce .NET packages issue