Wire up FlightSQL

[pauldix]

Use the service_grpc_flight crate to add FlightSQL functionality to Edge.

service_grpc_flight provides FlightService<S>, which wraps a service (S), which implements the trait QueryNamespaceProvider.

Therefore, to set up Edge for this, we need to implement the QueryNamespaceProvider trait, as well as the underlying QueryNamespace and QueryChunk traits for the Edge server. From there, we can use FlightService and tie it into the server to serve gRPC requests.