Certain aspnetcore packages not being built by VMR

[wtgodbe]

The following packages don't get built by the VMR:

BuildAfterTargetingPack
Microsoft.AspNetCore.AzureAppServices.SiteExtension.10.0.x64
Microsoft.AspNetCore.AzureAppServices.SiteExtension.10.0.x86
Microsoft.Internal.Aspnetcore.DotNetApiDocs.Transport
AspNetCoreRuntime.10.0.x64
AspNetCoreRuntime.10.0.x86
Microsoft.AspNetCore.AzureAppServices.SiteExtension
Microsoft.AspNetCore.Grpc.JsonTranscoding
Microsoft.AspNetCore.Grpc.Swagger

Some are probably intentional (BuildAfterTargetingPack), some are SiteExtensions, which will require some fiddling in eng/build.props, and some additions to DotNetBuildPass=2. The Grpc ones are likely real issues as well and should be investigated

[wtgodbe]

#60147 should fix the GRPC ones