Make the library work with GRPC

[SeanFarrow]

This may already work, but if it does not, it would be nice if the library worked with GRPC.

If it does, it would be nice to have a sample.

[stevejgordon]

@SeanFarrow This should work without any changes for incoming IDs as everything still works on top of ASP.NET Core and middleware regardless of whether the app handles gRPC requests or HTTP calls.

For passing the ID onto a downstream gRPC service, the new delegating handler for the 3.0.0 preview should work too, since gRPC client is based on HttpClient. It will just need to be added to the handler chain.

I'll review whether a separate sample is necessary.