Microsoft.DotNet.ApiSymbolExtensions binary is missing from the SDK, causing API compat failures in 8.0

[agocke]

Appears to have been introduced by #28855

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

@dotnet/area-infrastructure-libraries a new issue has been filed in the ApiCompat area, please triage