nil LocalAddr() crashes gRPC rbac engine

[dottana]

• Integrate gNSI interceptor with allow-all protocol policy into gRPC.

• Set up a gRPC tunnel from server to client defined in here

• The client uses the tunnel but sets the LocalAddr() to nil here.

• gRPC crashes at this line in an attempt to invoke String() on a nil object.

Related issue: https://github.com/grpc/grpc-go/issues/6384 @marcushines @gcsl @jxx-gg

[dottana]

Hi @gcsl @jxx-gg @marcushines Can you take a look at the issue, thank you!