Add GraalVM example for gRPC server

[vyshane]

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@jamesward has recently added an example of GraalVM usage with a gRPC client.

It would be awesome if we also had an example implementation of a gRPC server that runs via GraalVM :)

[jamesward]

I tried this but run into an issue: https://github.com/oracle/graal/issues/3052