dotnet-sos comes with libSOS for MSFT supported platforms: https://nuget.info/packages/dotnet-sos/9.0.621003. During the source-build, it doesn't get built. We should build the nupkg and include it under <install prefix>/library-packs so dotnet tool install --global dotnet-sos picks it up from the bundle on community platforms like linux-riscv64.

Proposed actions:

• in diagnostics repo: remove SourceBuildManagedOnly from https://github.com/dotnet/diagnostics/blob/22431fb5bfe047454e652a7274f4b4bc4b367527/eng/DotNetBuild.props#L6
• in SDK repo: add it to the bundled package

  sdk/src/Layout/redist/targets/RestoreLayout.targets

  Line 79 in e5f35a2

  <ItemGroup>

cc @mikem8361, @hoyosjs